How do I sign different versions of a silkscreen print?

Hello, I'm hoping someone can help me out. I know the basics of how to sign a silkscreen print, HOWEVER, I have a couple of prints where I switched up the colors. It's the same image, with the same title, but they can't all be one edition, right? Because an edition has to be identical, and this is two different versions. So how would I sign and number them? They're not going to have a different title, so I can't differentiate them that way. I've read that you can have a second edition of a print, but from what I've seen it sounds like that's for doing a second run if you want more of the original print. I haven't been able to find anything about how to indicate a different version.

I'm going to see my professor on Saturday, but I would like to get it done sooner. If anyone knows the proper way to sign them it would be much appreciated!