Giving a mimicrab the potion effect revival allows you to dupe items.

Step 1: Drop item you want to dupe in front of mimicrab
Step 2: Give mimicrab revival potion effect
Step 3: Kill mimicrab once
Step 4: Collect item or let mimicrab collect it
Step 5: Rinse and repeat or kill mimicrab

Fixed in the branch f75a1b0