What does the 'C_#' mean after an instance?

Hey, quick question. So I’ve been working on saving my project, and I was doing some debugging 'cause things weren’t functioning right. It seems fixed now, but I was wondering… After I promote the loaded game to a variable, I look at the return value, and at the end of the instance there’s a ‘C’, underscore, then a number. The number is always incremented, so I’m wondering if I’m saving right. Should a save game instance always be the same, or does the number at the end increment each time you load from the slot?