@Test
	public void testAddSameExternalFunctionNoConflict() throws Exception {

		final String libname = "user32.dll";
		final String parentNamespace = "MyNamespace";
		final String label = "apple";
		final String address = "0x100";

		mtf.initialize("NotepadMergeListingTest", new MergeProgramModifier() {

			@Override
			public void initializeProgram(MergeProgram program) throws Exception {
				program.addMemory("memory", "0x0", 0x200);
			}

			@Override
			public void modifyLatest(MergeProgram mergeProgram) throws Exception {
				Library library =
					mergeProgram.createExternalLibrary(libname, SourceType.USER_DEFINED);
				Namespace namespace =
					mergeProgram.createNamespace(library, parentNamespace, SourceType.USER_DEFINED);
				mergeProgram.addExternalFunction(namespace, label, address,
					SourceType.USER_DEFINED);
			}

			@Override
			public void modifyPrivate(MergeProgram mergeProgram) throws Exception {
				Library library =
					mergeProgram.createExternalLibrary(libname, SourceType.USER_DEFINED);
				Namespace namespace =
					mergeProgram.createNamespace(library, parentNamespace, SourceType.USER_DEFINED);
				mergeProgram.addExternalFunction(namespace, label, address,
					SourceType.USER_DEFINED);
			}
		});

		executeMerge(ASK_USER);
		waitForMergeCompletion();

		Namespace externalLibrary =
			(Namespace) resultProgram.getSymbolTable().getLibrarySymbol(libname).getObject();
		assertNotNull(externalLibrary);
		Namespace myNamespace =
			(Namespace) getUniqueSymbol(resultProgram, parentNamespace, externalLibrary)
					.getObject();
		assertNotNull(myNamespace);
		Symbol apples = getUniqueSymbol(resultProgram, label, myNamespace);
		Symbol applesConflict = getUniqueSymbol(resultProgram, label + "_conflict1", myNamespace);
		assertEquals(SymbolType.FUNCTION, apples.getSymbolType());
		assertNull(applesConflict);
	}
The external function merger only detects and merges source differences when a name
difference is being merged.
Ghidra/Features/Base/src/test.slow/java/ghidra/app/merge/listing/ExternalMergerAddTest.java