not same unit but same rule
Age of sigmar FAQ
Q: A Shadowblade Assassin that is hiding in a unit is set up at the start of the combat phase, and can then pile in and attack. If several Assassins are revealed at the same time, do they all get to pile in and attack before the enemy picks any units to attackwith? And are they allowed to pile in and attack a second time later in the combat phase? What if both sides have Assassins hidden in units?
A: The Assassins are revealed one at a time, and make their attack for that combat phase immediately after they are set up, before any enemy units get to attack. They cannot be selected to attack a second time in the same combat phase. If both players want to reveal Assassins, the player whose turn is taking place reveals their assassins first.