REGRESSION: Yes. Does not occur in 4.16.3
Using Copy/Paste to duplicate a component will result in a broken duplicate component. This doesn't occur if the user uses Ctrl+W to duplicate.
On compile, the user will either crash (see callstack), or generate a compile error:
Internal Compiler Error: Tried to create a property DefaultSceneRoot_GEN_VARIABLE in scope NewBlueprint_C, but another object (SceneComponent DefaultSceneRoot_GEN_VARIABLE) already already exists there.
RESULT
Duplicate component has odd name, and either the blueprint will error on compile, or crash.
UE4Editor_Kismet!FSCSEditorViewportClient::GetWidgetCoordSystem() scseditorviewportclient.cpp:694 UE4Editor_UnrealEd!FWidget::Render() unrealwidget.cpp:285 UE4Editor_UnrealEd!FEditorViewportClient::Draw() editorviewportclient.cpp:3516 UE4Editor_Kismet!FSCSEditorViewportClient::Draw() scseditorviewportclient.cpp:213 UE4Editor_Renderer!FSceneRenderer::FSceneRenderer() scenerendering.cpp:1225 UE4Editor_Renderer!FDeferredShadingSceneRenderer::FDeferredShadingSceneRenderer() deferredshadingrenderer.cpp:213 UE4Editor_Renderer!FRendererModule::BeginRenderingViewFamily() scenerendering.cpp:2009 UE4Editor_UnrealEd!FEditorViewportClient::Draw() editorviewportclient.cpp:3396 UE4Editor_Engine!FViewport::Draw() unrealclient.cpp:1198 UE4Editor_UnrealEd!UEditorEngine::UpdateSingleViewportClient() editorengine.cpp:2029 UE4Editor_UnrealEd!UEditorEngine::Tick() editorengine.cpp:1802 UE4Editor_UnrealEd!UUnrealEdEngine::Tick() unrealedengine.cpp:396 UE4Editor!FEngineLoop::Tick() launchengineloop.cpp:3215 UE4Editor!GuardedMain() launch.cpp:166 UE4Editor!GuardedMainWrapper() launchwindows.cpp:134 UE4Editor!WinMain() launchwindows.cpp:210 UE4Editor!__scrt_common_main_seh() exe_common.inl:253 kernel32!<Unknown> ntdll!<Unknown>
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-47834 in the post.