Bruce, I've been on both sides of that happening, replacing existing scans with better ones and having mine also replaced. For all I know I might have replaced one of yours and if so, sorry 'bout that.
It does kind of suck to have your scans replaced, I know what you mean.
And I've thought about keeping both submitter's names but after seeing one like that happen to me that I'm a part of I can say, I'd rather the other guy get the credit. I really do. I figure if someone submits a noticeably better scan they should get the credit, it's a better scan and it's the one now being used.
Honestly, I just want the best scans possible in there.
But I know what you mean.