MC 1.19.2; Requiem 2.0.0-beta.16; Trinkets 3.4.2

• When shift-equipping a Trinket, the item will (more likely than not) equip to multiple Trinket slots, the extra of which are supposed to be invalid (i.e. a 'Shoes' Trinket should not be equipable to 'Face', yet it does); these can be removed, and the process repeated to generate infinite copies of the item.
• When moving a Trinket by cursor to hotbar slot 1, the item is copied to the 'Face' Trinket slot.
• With 'Artifacts' installed, moving a Trinket to hotbar slot 2 copies the item to the extra off-hand 'Glove' slot.
• Doing all of these things in random order with various Trinkets causes increasingly complex and inexplicable duplications.

Mods:

• Cardinal Components 5.0.2 (Trinkets dependency)
• Cloth Config API 8.2.88-fabric (Things dependency)
• owo-lib 0.9.3 (Things dependency)
• Patchouli 1.19.2-77-FABRIC (Things dependency)
• QFAPI 4.0.0-beta.30 & QSL 3.0.0-beta.29
• Requiem 2.0.0-beta.16
• Things 0.3.0 (Trinkets dependent for dupe testing)
• Trinkets 3.4.2

It’s a 100% serverside port, which makes it incredibly hard to get any useful information out of. I’ve also experienced this issue while testing various modpacks without requiem, and the same appears to happen, so it’s a common issue really.

Known workaround is to use Patbox's Polymer port of Trinkets. Although this fork naturally comes with some spare jank when interacting with other mods, the issue I've described here does not occur. May want to cross-examine and see what each does differently, if that's useful.

@Pyrofab Do you have any suspicions what could be causing this?

Possibly Locki ? I believe it's the only library in Requiem which significantly touches the inventory

update: the mod specifically causing it was Requiem. not sure why.

i've had this issue before too, though it's not just trinkets: it's any item I put in my first slot in creative mode specifically. Sometimes, even taking duped items out of the slots or even shift clicking empty armor slots causes duping.