Using MIME types in addition to plugin name to differentiate between plugins.

chrome/browser/resources/plugin_metadata/plugins_mac.json

 {
   "google-talk": {
     "mime_types": [
     ],
     "versions": [
       {
         "version": "0",
         "status": "up_to_date",
         "comment": "'Google Talk Plugin' and 'Google Talk Plugin Video Accelerator' use two completely different versioning schemes, so we can't define a minimum version."
       }
     ],
     "name": "Google Talk",
     "group_name_matcher": "Google Talk"
   },
   "java-runtime-environment": {
     "mime_types": [
-      "application/x-java-applet",
-      "application/x-java-applet,version=1.1",
-      "application/x-java-applet,version=1.1.1",
-      "application/x-java-applet,version=1.1.2",
-      "application/x-java-applet,version=1.1.3",
-      "application/x-java-applet,version=1.2",
-      "application/x-java-applet,version=1.2.1",
-      "application/x-java-applet,version=1.2.2",
-      "application/x-java-applet,version=1.3",
-      "application/x-java-applet,version=1.3.1",
-      "application/x-java-applet,version=1.4",
-      "application/x-java-applet,version=1.4.1",
-      "application/x-java-applet,version=1.4.2",
-      "application/x-java-applet,version=1.5",
-      "application/x-java-applet,version=1.6",
-      "application/x-java-bean",
-      "application/x-java-bean,version=1.1",
-      "application/x-java-bean,version=1.1.1",
-      "application/x-java-bean,version=1.1.2",
-      "application/x-java-bean,version=1.1.3",
-      "application/x-java-bean,version=1.2",
-      "application/x-java-bean,version=1.2.1",
-      "application/x-java-bean,version=1.2.2",
-      "application/x-java-bean,version=1.3",
-      "application/x-java-bean,version=1.3.1",
-      "application/x-java-bean,version=1.4",
-      "application/x-java-bean,version=1.4.1",
-      "application/x-java-bean,version=1.4.2",
-      "application/x-java-bean,version=1.5",
-      "application/x-java-bean,version=1.6",
-      "application/x-java-vm"
+      { "mime_type": "application/x-java-applet" },
+      { "mime_type": "application/x-java-applet,version=1.1" },
+      { "mime_type": "application/x-java-applet,version=1.1.1" },
+      { "mime_type": "application/x-java-applet,version=1.1.2" },
+      { "mime_type": "application/x-java-applet,version=1.1.3" },
+      { "mime_type": "application/x-java-applet,version=1.2" },
+      { "mime_type": "application/x-java-applet,version=1.2.1" },
+      { "mime_type": "application/x-java-applet,version=1.2.2" },
+      { "mime_type": "application/x-java-applet,version=1.3" },
+      { "mime_type": "application/x-java-applet,version=1.3.1" },
+      { "mime_type": "application/x-java-applet,version=1.4" },
+      { "mime_type": "application/x-java-applet,version=1.4.1" },
+      { "mime_type": "application/x-java-applet,version=1.4.2" },
+      { "mime_type": "application/x-java-applet,version=1.5" },
+      { "mime_type": "application/x-java-applet,version=1.6" },
+      { "mime_type": "application/x-java-bean" },
+      { "mime_type": "application/x-java-bean,version=1.1" },
+      { "mime_type": "application/x-java-bean,version=1.1.1" },
+      { "mime_type": "application/x-java-bean,version=1.1.2" },
+      { "mime_type": "application/x-java-bean,version=1.1.3" },
+      { "mime_type": "application/x-java-bean,version=1.2" },
+      { "mime_type": "application/x-java-bean,version=1.2.1" },
+      { "mime_type": "application/x-java-bean,version=1.2.2" },
+      { "mime_type": "application/x-java-bean,version=1.3" },
+      { "mime_type": "application/x-java-bean,version=1.3.1" },
+      { "mime_type": "application/x-java-bean,version=1.4" },
+      { "mime_type": "application/x-java-bean,version=1.4.1" },
+      { "mime_type": "application/x-java-bean,version=1.4.2" },
+      { "mime_type": "application/x-java-bean,version=1.5" },
+      { "mime_type": "application/x-java-bean,version=1.6" },
+      { "mime_type": "application/x-java-vm" }
     ],
     "versions": [
       {
         "version": "12.8.0",
         "status": "requires_authorization",
         "comment": "Leopard"
       },
       {
         "version": "13",
         "status": "out_of_date"
@@ skipping 15 matching lines @@
     ],
     "lang": "en-US",
     "name": "Java(TM)",
     "url": "http://java.com/en/download/apple_manual.jsp",
     "help_url": "https://support.google.com/chrome/?p=plugin_java",
     "displayurl": true,
     "group_name_matcher": "Java"
   },
   "realplayer": {
     "mime_types": [
-      "audio/vnd.rn-realaudio",
-      "video/vnd.rn-realvideo",
-      "audio/x-pn-realaudio-plugin",
-      "audio/x-pn-realaudio"
+      { "mime_type": "audio/vnd.rn-realaudio" },
+      { "mime_type": "video/vnd.rn-realvideo" },
+      { "mime_type": "audio/x-pn-realaudio-plugin" },
+      { "mime_type": "audio/x-pn-realaudio" }
     ],
     "versions": [
       {
         "version": "0",
         "status": "requires_authorization",
         "comment": "The Real Player plug-in for mac doesn't expose a version at all."
       }
     ],
     "lang": "en-US",
     "name": "RealPlayer",
     "url": "http://director.real.com/realplayer?type=rpsp_mac",
     "help_url": "https://support.google.com/chrome/?p=plugin_real",
     "group_name_matcher": "RealPlayer"
   },
   "adobe-flash-player": {
     "mime_types": [
-      "application/futuresplash",
-      "application/x-shockwave-flash"
+      { "mime_type": "application/futuresplash" },
+      { "mime_type": "application/x-shockwave-flash" }
     ],
     "versions": [
       {
         "version": "11.1.102",
         "status": "up_to_date",
         "reference": "http://www.adobe.com/support/security/bulletins/apsb12-03.html"
       }
     ],
     "lang": "en-US",
     "name": "Adobe Flash Player",
     "url": "http://get.adobe.com/flashplayer/",
     "help_url": "https://support.google.com/chrome/?p=plugin_flash",
     "displayurl": true,
     "group_name_matcher": "Shockwave Flash"
   },
   "adobe-shockwave": {
     "mime_types": [
-      "application/x-director"
+      { "mime_type": "application/x-director" }
     ],
     "versions": [
       {
         "version": "11.6.6.636",
         "status": "requires_authorization",
         "reference": "http://www.adobe.com/support/security/bulletins/apsb12-17.html"
       }
     ],
     "lang": "en-US",
     "name": "Adobe Shockwave Player",
     "url": "http://fpdownload.macromedia.com/get/shockwave/default/english/macosx/latest/Shockwave_Installer_Full_64bit.dmg",
     "help_url": "https://support.google.com/chrome/?p=plugin_shockwave",
     "group_name_matcher": "Shockwave for Director"
   },
   "apple-quicktime": {
     "mime_types": [
-      "application/sdp",
-      "application/x-mpeg",
-      "application/x-rtsp",
-      "application/x-sdp",
-      "audio/3ggp",
-      "audio/3ggp2",
-      "audio/aac",
-      "audio/ac3",
-      "audio/aiff",
-      "audio/amr",
-      "audio/basic",
-      "audio/mid",
-      "audio/midi",
-      "audio/mp4",
-      "audio/mpeg",
-      "audio/vnd.qcelp",
-      "audio/wav",
-      "audio/x-aac",
-      "audio/x-ac3",
-      "audio/x-aiff",
-      "audio/x-caf",
-      "audio/x-gsm",
-      "audio/x-m4a",
-      "audio/x-m4b",
-      "audio/x-m4p",
-      "audio/x-midi",
-      "audio/x-mpeg",
-      "audio/x-wav",
-      "image/jp2",
-      "image/jpeg2000",
-      "image/jpeg2000-image",
-      "image/pict",
-      "image/png",
-      "image/x-jpeg2000-image",
-      "image/x-macpaint",
-      "image/x-pict",
-      "image/x-png",
-      "image/x-quicktime",
-      "image/x-sgi",
-      "image/x-targa",
-      "video/3ggp",
-      "video/3ggp2",
-      "video/flc",
-      "video/mp4",
-      "video/mpeg",
-      "video/quicktime",
-      "video/sd-video",
-      "video/x-m4v",
-      "video/x-mpeg"
+      { "mime_type": "application/sdp" },
+      { "mime_type": "application/x-mpeg" },
+      { "mime_type": "application/x-rtsp" },
+      { "mime_type": "application/x-sdp" },
+      { "mime_type": "audio/3ggp" },
+      { "mime_type": "audio/3ggp2" },
+      { "mime_type": "audio/aac" },
+      { "mime_type": "audio/ac3" },
+      { "mime_type": "audio/aiff" },
+      { "mime_type": "audio/amr" },
+      { "mime_type": "audio/basic" },
+      { "mime_type": "audio/mid" },
+      { "mime_type": "audio/midi" },
+      { "mime_type": "audio/mp4" },
+      { "mime_type": "audio/mpeg" },
+      { "mime_type": "audio/vnd.qcelp" },
+      { "mime_type": "audio/wav" },
+      { "mime_type": "audio/x-aac" },
+      { "mime_type": "audio/x-ac3" },
+      { "mime_type": "audio/x-aiff" },
+      { "mime_type": "audio/x-caf" },
+      { "mime_type": "audio/x-gsm" },
+      { "mime_type": "audio/x-m4a" },
+      { "mime_type": "audio/x-m4b" },
+      { "mime_type": "audio/x-m4p" },
+      { "mime_type": "audio/x-midi" },
+      { "mime_type": "audio/x-mpeg" },
+      { "mime_type": "audio/x-wav" },
+      { "mime_type": "image/jp2" },
+      { "mime_type": "image/jpeg2000" },
+      { "mime_type": "image/jpeg2000-image" },
+      { "mime_type": "image/pict" },
+      { "mime_type": "image/png" },
+      { "mime_type": "image/x-jpeg2000-image" },
+      { "mime_type": "image/x-macpaint" },
+      { "mime_type": "image/x-pict" },
+      { "mime_type": "image/x-png" },
+      { "mime_type": "image/x-quicktime" },
+      { "mime_type": "image/x-sgi" },
+      { "mime_type": "image/x-targa" },
+      { "mime_type": "video/3ggp" },
+      { "mime_type": "video/3ggp2" },
+      { "mime_type": "video/flc" },
+      { "mime_type": "video/mp4" },
+      { "mime_type": "video/mpeg" },
+      { "mime_type": "video/quicktime" },
+      { "mime_type": "video/sd-video" },
+      { "mime_type": "video/x-m4v" },
+      { "mime_type": "video/x-mpeg" }
     ],
     "versions": [
       {
         "version": "7.6.6",
         "status": "requires_authorization"
       }
     ],
     "lang": "en-US",
     "name": "QuickTime Player",
     "url": "http://www.apple.com/quicktime/download/",
     "help_url": "https://support.google.com/chrome/?p=plugin_quicktime",
     "displayurl": true,
     "group_name_matcher": "QuickTime Plug-in"
   },
   "flip4mac": {
     "mime_types": [
-      "application/asx",
-      "application/x-mplayer2",
-      "application/x-ms-wmp",
-      "audio/x-ms-wax",
-      "audio/x-ms-wma",
-      "video/x-ms-asf",
-      "video/x-ms-asf-plugin",
-      "video/x-ms-wm",
-      "video/x-ms-wmv",
-      "video/x-ms-wvx"
+      { "mime_type": "application/asx" },
+      { "mime_type": "application/x-mplayer2" },
+      { "mime_type": "application/x-ms-wmp" },
+      { "mime_type": "audio/x-ms-wax" },
+      { "mime_type": "audio/x-ms-wma" },
+      { "mime_type": "video/x-ms-asf" },
+      { "mime_type": "video/x-ms-asf-plugin" },
+      { "mime_type": "video/x-ms-wm" },
+      { "mime_type": "video/x-ms-wmv" },
+      { "mime_type": "video/x-ms-wvx" }
     ],
     "versions": [
       {
         "version": "2.2.1",
         "status": "requires_authorization"
       }
     ],
     "lang": "en-US",
     "name": "Flip4Mac",
     "url": "http://www.microsoft.com/download/en/confirmation.aspx?id=9442",
     "help_url": "https://support.google.com/chrome/?p=plugin_wmp",
     "displayurl": true,
     "group_name_matcher": "Flip4Mac"
   },
   "divx-player": {
     "mime_types": [
-      "video/divx",
-      "video/x-matroska"
+      { "mime_type": "video/divx" },
+      { "mime_type": "video/x-matroska" }
     ],
     "versions": [
       {
         "version": "2.2",
         "status": "requires_authorization"
       }
     ],
     "lang": "en-US",
     "name": "DivX Web Player",
     "url": "http://www.divx.com/en/downloads/divx/mac",
     "help_url": "https://support.google.com/chrome/?p=plugin_divx",
     "group_name_matcher": "DivX Plus Web Player"
   },
   "silverlight": {
     "mime_types": [
-      "application/x-silverlight",
-      "application/x-silverlight-2"
+      { "mime_type": "application/x-silverlight" },
+      { "mime_type": "application/x-silverlight-2" }
     ],
     "versions": [
       {
         "version": "4.1.10111.0",
         "status": "up_to_date",
         "reference": "http://support.microsoft.com/kb/2668562"
       }
     ],
     "lang": "en-US",
     "name": "Silverlight",
     "url": "http://go.microsoft.com/fwlink/?LinkID=149156",
     "displayurl": true,
     "group_name_matcher": "Silverlight"
   },
   "google-chrome-pdf": {
     "mime_types": [
     ],
     "versions": [
       {
         "version": "0",
         "status": "up_to_date",
         "comment": "Chrome PDF Viewer has no version information."
       }
     ],
     "name": "Chrome PDF Viewer",
     "group_name_matcher": "Chrome PDF Viewer"
   }
 }