I've removed all the duplicates and the count is now accurate (10666 of 10678). Just 12 discs left!
Eight are missing and listed under "Missing/Outdated games" while the other four are outdated and not currently listed. I'll probably just delete them so they'll show up as "missing" too.

Yes, I was looking at that last night and the discrepancy is due to duplicate records. I should be able to craft a query to identify them all.
MediEvil's an odd duck due to its double digit betas. The Vault assigns each beta a unique version number starting with 0.1. That's a problem when you reach beta 10, since mathematically 0.1 == 0.10
Perhaps I should start at v0.01 instead.