Stack unstackable items and stackable items past 64

Reproduction
Throw two of the same unstackable item on the ground and pick it up. You will get a stack of 2.

Throw a stack of 64 and a single item of a stackable item on the ground and pick it up. You will get a stack of 65.

If you attempt to pickup a stack higher than 127, it will disappear. Minecraft can only handle stacks below 128.