That's...not normal. You're the first to report, I believe.
What happens if you close the additional copies?
What happens when you create a new project, save it, close it and reopen it?
It seems to happen often, but not all the time. Sometimes it will open a whole lot like in the image and I have to close each one until it's down to only one, but sometimes it will just open one. It's very sporadic. It doesn't affect work flow, it's just a bit annoying having to close them all.
Is this a new 12.1 project or one you updated from 12.0.x? Let us know.
Stuck mouse button or keyboard button?
Very great idea Bob. I believe on occasion my ASUS laptop power button has been sticky and while it does start up on a few occasions the computer turns right off. I think you solved that one for me. I have got to get a compressed air bottle to see if I can clean around the power button with about 4-years of heavy usage.
If you have this keyboard option try changing the settings