If a stack of bundles or shulkers is dropped as an item and destroyed it will only drop for one.

To Reproduce:

1. /give @s bundle[minecraft:max_stack_size=2]
2. place atleast one item in the bundle
3. copy with middle mouse click
4. drop whole stack onto the ground
5. /summon tnt
6. pick up remaining items and notice there is only the quantity of a single bundle, not multiple