I've recently done this!
Basically, for me, I don't always recognise rares or up when looking through the pound. So occasionally, I'd see a pet I thought was rare, and it turned out it absolutely wasn't. So now, if it's on my wishlist, it's either a pet I genuinely want, or at least a rare I can trade on.
Sometimes now, when I'm trading, I'm like 'oh that's a really rare pet I'm hoping to collect!', but all I have to do is check in the archive and it'll say whether I've already got it or not, and then I know.
Basically, for me, I don't always recognise rares or up when looking through the pound. So occasionally, I'd see a pet I thought was rare, and it turned out it absolutely wasn't. So now, if it's on my wishlist, it's either a pet I genuinely want, or at least a rare I can trade on.
Sometimes now, when I'm trading, I'm like 'oh that's a really rare pet I'm hoping to collect!', but all I have to do is check in the archive and it'll say whether I've already got it or not, and then I know.