Teams consisted of Thor, Mystique, Deadpool vs. Wolverine, Commander, The Hulk. The enemy used All Tied Up from Spider-Man (Classic), but it somehow managed to stun both Mystique and Deadpool.
I had the same experience.
Happened to me in a PvP match more than once. I cannot tell what the preceding circumstances were though.
Preceding circumstances: r92 released
Or a stealth buff to Spideys stun? Heh, yeah, I realise this is just wishful thinking 
Regards,
Cypr3ss
Happened to me today as well in the DDQ node, he stunned two of my team-mates. At first I didn’t knew wtf was going on, thought Mistique did her purple followed by Spiderman’s blue but there was no purple cd tile in sight, which led to the conclusion that i was Spiderman’s attack that stunned both of my guys all along.