Watering can dupe

I haven't tried to replicate
Made 9 simple watering cans, using Gneiss, wood and tier 2 prey pelt
Went to the simple upgrade bench, and upgraded all 9 to tier 2
Somehow it crafted 62, gear score 45, tier 2 watering cans

Edit: it overfilled my inventory to more than 75 slots, I do not recall how much more it filled up

Edit2: I added a screenshot, incase you need more clarification, I only crafted 9 of these