Dispenser dispenses two wither skeleton skulls istead of one if a mob or a player is right next to it

Description:

If you put 2 or more wither skeleton skulls in the dispenser and put a player or mob (for example, villager) next to it, then activate the dispenser, it will drop one wither skeleton skull on the ground AND put another one on a villager (note that only one redstone signal was given)

How to recreate:

1) Place a dispenser and put 2 or more wither skeleton skulls in it

2) Put a villager next to it or any player

3) Activate a dispenser

What should happen?

The dispenser should only put a wither skeleton skull on villager's head

What happens?

The dispenser puts one wither skeleton skull on the villager and drops another one on the ground all in one redstone signal