Removing Duplicates doesn't remove newest item

I am using a second collection to come up with a list of PS3 exclusives. I am doing this by importing a list of Xbox 360 games first and then later a list of PS3 games. Using the manage duplicates tool it should be expected that any matches would remove the PS3 game since it is newer but instead it removes some PS3 and some Xbox 360 games seemingly at random.

I’m not entirely sure what the order of doing things here, is but I believe the Find Duplicates system would remove the duplicate that was entered first into your collection (not by release date, but by added date), and keep the newest (the one that was entered last).

But, you can also manually just click one to remove in the list of found duplicates!

Yeah that’s the problem, it’s not always keeping the oldest added item. I’m importing then360 games first, then ps3, then going to remove duplicates. I even waited a few hours so that the added dates are different and it didn’t matter. There are about 850 duplicates and it seems like 500 ish of them are removed correctly while the others remove the older game.