Objects have the same fully qualified name but different paths. Use UE4.21.0

WHY?

[2018.11.21-07.43.44:399] 0]LogWindows: Error: Fatal error: [File:E:\UnrealEngine-release\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectGlobals.cpp] [Line: 2387]
[2018.11.21-07.43.44:399] 0]LogWindows: Error: Objects have the same fully qualified name but different paths.
[2018.11.21-07.43.44:399] 0]LogWindows: Error: New Object: ObjectProperty /Game/MMO/Blueprints/Chat/ChatWidget.ChatWidget_C.ChatInput
[2018.11.21-07.43.44:399] 0]LogWindows: Error: Existing Object: StrProperty /Game/MMO/Blueprints/Chat/ChatWidget.ChatWidget_C:ChatInput

This seems to be related to restarting the engine after hot reloads as outlined here: https://answers.unrealengine.com/questions/663483/bug-objects-have-the-same-fully-qualified-name-but.html
The alleged fix from 4.18 seems no longer to work - you can work around it and force a recompile by manually deleting the binaries folder in your project directory before opening the project.