Unknown node drop is happening

After editing some properties of a node1, if I drag and drop another node (defined to sit in a different layer and inside bubble group) on the canvas (while there is still some updates happening in the background related to the property edit operation), it is triggering a dropping of node1 with the same key as the existing one and eventually fails to get added.
The call stack shows Array.concat.xf.doSimulatedDrop as the initiator of the call.
Could some one explain why/what scenarios would cause this?

Thanks!

There are a lot of conditions in your situation. Could you please explain them? I have no idea of what your app looks like and what is happening during the drag-and-drop and what it is that you want to happen instead.