I'll note that I opened this project file that was created in version 4 so it may be related to that.
In the 2D view, there is an icon of my Sheds wash-spot light that will not move, but if I click and drag it somewhere, it will create a copy of the icon each time I click it (circled in red). The fixture is not really there in the universe, just this icon in the 2D view.
The exact fixture causing this is the
<Manufacturer>Shehds</Manufacturer>
<Model>LED Beam+Wash 19x15W RGBW Zoom Lighting</Model>