The glitch at the Trial Road Dungeon makes copies of items in the artifact inventories of the shops. From the time that Moapa opens the dungeon and until Felix beats Moapa every item that Felix and friends drop will be returned to Felix’ inventory when he leaves Trial Road. Entering dropped items in the artifact inventory of the shops is already part of the game design. Only the Laughing Fungus, Large Bread, Bone, Smoke Bombs, Sleep Bombs, Bramble Seeds, Oil Drops, Crystal Powder, and Weasel Claws will not be copied to the shop inventory.

When you enter trial road as soon as you control Felix drop an item you want to duplicate and then leave Trial Road. Go to an item shop and buy the duplicates of the item you dropped.

This can be used to duplicate Hyper Boots, the Swift Sword, Tear Stone, Lucky Medals, and Waters of Life.