Oh god there's a horrible dupe glitch with the rift about cascade2

[quat1024]

Fixed.

Was caused by not copying the recipe's output ItemStack. Looks like EntityItems don't copy it either in their constructor, and since Java objects pass by reference the EntityItems were all keeping a pointer to the same ItemStack used in the RiftRecipe output. Presumably when the item entities created from the rift in this way merged (in the way item entities do), one of the entities changed the count on the other's ItemStack. This ItemStack was of course the same stack that the RiftRecipe was holding on to, so the recipe progressively produced more and more items every time items merged together.

Oops.

Fixed by returning a copy of the ItemStack instead of a reference to it.