I reported earlier an issue with the debugger showing 2 object types for the one object (same UID), and now I'm seeing more weird stuff.
I had an issue with a layout where ScrollTo wasn't scrolling, and also a background image wasn't displaying. So I just duplicated the layout and used that instead, and both issues went away! I did a diff between the 2 layout.xml files and the only differences were uid and sid values.. So how does that work? It's the second layout today I've had to do that.
tldr: issues with layout; duplicate it; issues go away
Better report it to a bugs section, i've recently reported a bug with "Reset persisted objects" that cause objects to duplicate(with uid), maybe now something else broken, but now it's not an action, maybe now it's something in the engine that resets or spawn the objects.