I'm not 100% sure on this.
I only know of the invisible creature thing because I forgot to bring in his physique file one time and that was the result.
I'm only assuming, but if you did it the other way around, the game might create a new mind file with the appropriate name and you'd have to start from scratch again.
However, if you shut down the game and over-ride it with the proper mind file, I think everything should be good again :
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
: .
As for renaming the files, it doesn't work like that. The profile you are playing is tied into the creature mind file, so if you rename it, the profile can't find and load it.
However this can work to your advantage as well in that you can swap out creatures from other profiles into yours by simply renaming the creature mind and physique files to the one your profile uses :
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
: . Make sure you back up your own creature first though if you don't want to loose him.
This technique is handy if your save games in your current profile become corrupted. You can start a new profile and then bring in your old creature using this method :yes .