Regarding the Brilliant Love: IM URS! 2019 Valentines Day Hat.

Bug or Intentional? Players can practically get an unlimited amount of this hat

Brilliant Love: IM URS!
Attachment 175656

My theory:
Attachment 175658

I asked for the user, 'Vaspid' to test out my theory for me and together, we bagged an example for you:

https://gyazo.com/f3553320fc21d8e92c65f5d5e145e895.gif

That's how it works - you should be able to get one if you don't have it in inventory or stash.