Issue 13787. It is OK to export same element twice.

tests/language/language_analyzer.status

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 [ $compiler == dartanalyzer ]
 # Runtime negative test. No static errors or warnings.
 closure_call_wrong_argument_count_negative_test: skip
 
 # Test issue 12694 (was analyzer issue), (1) when "abstract" is import prefix using it as type is warning; (2) currently analyzer resolves prefix as field (don't ask)
 built_in_identifier_prefix_test: CompileTimeError # Issue 12694
 
 # TBD: these look like bad tests, no issue number
 class_literal_test: fail
 constructor_call_as_function_test/01: fail
 
 function_type_alias9_test/00: crash # Issue 11987
 
 # TBF: we should check conflicts not only for methods, but for accessors too
 override_field_test/02: fail
 override_field_test/03: fail
 method_override7_test/03: Fail # Issue 11496
 
-export_double_same_main_test: Fail # Issue 14772
-
 # Please add new failing tests before this line.
 # Section below is for invalid tests.
 #
 #
 
 ref_before_declaration_test/07: fail # please triage
 ref_before_declaration_test/none: fail # please triage
 
 # test issue 11124, It is warning, not error to don't initialize final field
 field3a_negative_test: Fail # Issue 11124
@@ skipping 28 matching lines @@
 getter_no_setter_test/none: fail
 
 # test issue 11584, positional arguments cannot be used for named parameters
 compile_time_constant_e_test: fail
 
 # test issue 11585, static warning, not negative test
 constructor3_negative_test: fail
 constructor_call_wrong_argument_count_negative_test: fail
 instance_call_wrong_argument_count_negative_test: fail
 
-# test issue 11589, export D from 2 export directives
-export_cyclic_test: fail
-
 # test issue 11590, runtime only negative test
 field_method4_negative_test: fail
 
 # test issue 11592, Function type alias (typedef) is not a constant
 first_class_types_constants_test: fail
 
 # test issue 11594, Reference to a not resolve identifier is static warning
 import_combinators_negative_test: fail
 interface_static_non_final_fields_negative_test: fail
 
@@ skipping 36 matching lines @@
 
 # test issue 12539, rules for finals were loosened, contradiction in spec was fixed
 const_syntax_test/09: fail # Issue 12539
 
 # test issue 12541; there shouldn't be a static warning
 static_field_test/01: fail # Issue 12541
 static_field_test/02: fail # Issue 12541
 static_field_test/03: fail # Issue 12541
 static_field_test/04: fail # Issue 12541
 
-# test issue 13787; duplicate exports of the same declaration is not handled
-duplicate_export_test: fail # Issue 13787
-
 # test issue 13916, Looks as no warning should be in this redirecting factory
 redirecting_factory_infinite_steps_test/01: fail
 
 # test issue 14471, has (legitimate) static warning; but not annotated
 redirecting_factory_default_values_test/none: StaticWarning # Test issue 14471; has (legitimate) static warning; but not annotated
 
 # test issue 13956, It is a static type warning if any of the type arguments to k' are not subtypes of the bounds of the corresponding formal type parameters of type.
 default_factory2_test/none: fail
 
 # test issue 14021, it is warning, not an error to reference private (undefined) identifier
@@ skipping 300 matching lines @@
 type_variable_identifier_expression_test: StaticWarning
 type_variable_scope2_test: StaticWarning
 unary_plus_negative_test: CompileTimeError
 unbound_getter_test: StaticWarning
 unhandled_exception_negative_test: CompileTimeError
 unresolved_top_level_method_negative_test: CompileTimeError
 vm/type_cast_vm_test: StaticWarning
 vm/type_vm_test: StaticWarning
 void_type_test: StaticWarning