There is a glitch that occurs when playing older versions of the game (see resources for link to older version). If you discard an equipped item and then pick up an item of a different type (types as in weapons, earrings, tail accessories etc), the game auto-equips the new item, thus allowing you to equip multiple of any item type (max 5). However, stacks are reset when you try to equip any of the "fake" items.

Glitch discovered by PeteyGeens: