Often we have items in the database that are created with missing information. x item is created and everyone assumes it's the only variant. But sometimes, much later afterwards, someone realises that two or more variants of that item exists and it becomes necessary to create a second item to differenciate the two. In this instance, the original item gets changed to one of the two variants. But if I'm unlucky enough to own the second variant, since the original item now becomes the first variant, it creates an error in my collection database, because now it says I own an item which I don't actually own.
It happened to me once with item #1521 when it was found out there was a second variant of it, which was created as item #163912. One day I'm just browsing the PS2 section for fun and I notice the two, and realise the item I had added to my collection initially is now incorrect.
And now it just happened again with item #175417 and #211404. I own the latter, and thank god I logged on at the perfect moment to notice the new item in the Latest Items bar, because otherwise I would have been stuck with yet again an item rendered incorrect due to changes in its description.
We seriously need to implement a notification system for when items in your collection are modified, to avoid added items becoming retroactively incorrect. I'll have to go back and double check all of my 1000+ items in my collection now, because I'm starting to notice that at least a good amount of them have become incorrect over the years. Just imagine those with 10000+ items in their collection already!