Hmmm can you be more specific? If your talking about stun immunity then if someone is stunned for 2 seconds, they cannot be stunned for another 2 seconds after getting stunned. But I dont recall a stun ever "cancelling" a second stun. You have a replay of this? (can finally use replays )

Yes what Shiro_Sol said.  For example if you have two rooks on your team, they both boulder roll an opponent at the same time, the opponent does not get stunned.

this is the stuff ive encountered...

1. i stun someone then very soon after they recover and get stunned again, they r immune for the second stun.
2. Stuns being cancelled by skills like penitence and deep freeze.

but wat i have gathered is that tb can still freeze anyone with frost nova after any stun or during any stun(im pretty sure anyway).

Any idea what the rationale behind this being intentional would be?  Other then to punish a team for not coordinating their stuns, which seems unlikely  To me it seems more like an error in the coding of stun immunity.  I would just like some clarification that this is intentional.

Most likely the the intent was to simply prevent chain stunning a-la-DotA, where a common cause of death is losing control of your character for 6+ seconds. However, it seems to me that the cause of this glitch is the game's method of preventing stuns. The character is immune to the second stun, so stun effects are stripped off that character, including the first stun.

Not sure if it is intentional or not but it does require more co-ordination within a team and so raisies the skill ceiling of the game - which is needed atm.

this

And yes, it can be annoying

At the least, level 3 shields and heals should break stun on allies to compensate