So, I was normally playing solo, farming resources on that day/night forest, when I realized a very interesting thing.
I was swapping my weapon to a torch, to be able to run between places at night, and at one moment I accidentally put my Bow into an alredy occupied slot (dont actually know what was in it, but it was a stackable material, for sure) and... It duplicated! So now I had 2 tier 2 bows! I tried to do it several more times, and it works with ANY object you can equip on your character. All you need to do is grab any resource, and then just swap your equipped stuff with that resource. Ta da! Works even on stackable equippable items (I managed to duplicate grenades 3 times, and now I have 144 of them...)