First speed up Embers Rekindled's Melter,put an item into it.And then quick right click to dupe items.

accelerate mods refer to things like time in a bottle or Torcherino

Sorry for interupting you, but it's seem that this bug only occur when you stand on top of the melter and right click. If you stand on somewhere else and right click the melter with the item, the item won't be duped

In fact,I don't really care this bug now,so i'love close it at once