Does it get fixed when you restart Couatl after editing it ?
Because of how the editor works, which alternates between a traditional 2D dialog and the full 3D view, sometimes Simobjects created in editing mode get "stuck" even if we explicitly send a command to remove them, for a series of complex reasons that lies to how garbage collection works in Python and how it behaves differently when a 2d window with its own separate message loop enters into play.
We'll try to improve this but restarting Couatl might be a good workaround, because when a Simconnect clients disconnects, the simulator itself will surely clear every object which was created by it.