Splash potions with players error

Splash potions when thrown while a player is within 1 block in any direction, affect both players, but not the mobs or objects that they are thrown at. In my case, I tested this bug with speed, regen, instant regen, instant damage, strength, fire res, night vision, and water breathing. There is an attached video example using instant damage.

Note: The player's hitboxes were not touching in the testing.