I've both done this and had it happen to me.

The first occurance was when a first-time chip scan I contributed and was accredited for, was replaced by a better scan.

I was conflicted. I understand (and want) the best scan of a chip to appear in the ChipGuide. but my name as contributor was removed and replaced by the new contributor (as Jim Follis indicated above is the policy) - but I felt kind of lousy losing the acknowledgement. I have a modest collection of about 900 chips and jumped on the chance early in the effort to submit chips for inclusion and am proud of the fact that I have almost 100 chips in the ChipGuide.

I suggested to Charles that perhaps a modification could be made in cases like this, where both the original contributor's name along with new contributor's name could be displayed.

Charles saw my point and responded to me that he would consider that, but that was some time ago. Of course, the effort to do this could be either a small one or a monumental task - I understand that and do not criticize Charles or anyone else for not adopting my suggestion - The ChipGuide is an amazing achievement, one that everyone in this club should be proud of whether they've submitted scans or not.

Subsequently, I submitted a better scan of a chip already in the ChipGuide and got credit fir it.