I had this glitch where I could stack the viper helmet on top of Chaba's helmet.
I protested a bit and using this bug, I equipped several items at once creating crazy statistics, unfortunately after equipping a certain amount % DMG is no longer calculated correctly. I managed to equip 5 items in one slot at most.
to do this you need to use the item swap function after hovering one over the other. Dragging from the slot of equipped items to the item that you want to wear as the second one, however, do not place one perfectly over the other but move slightly to the right. Normally they should swap places but after some time they will change, however, in the inventory the item will be shifted relative to the slot. then we put the equipped item on it again and both return to the equipped slot.
if we want more than 2 we simply repeat the process.