Thanks for taking the time to read what I wrote, but I don't think its polite to shut down discussion by arbitrarily stating that someone else is correct and then ending it.
I read Bulallin's comments and if I didn't have a different opinion, I wouldn't have written anything here. Again, it is a single attack "that is treated" like two separate attacks (cluster missiles, duh).
/Shrug/
Like I said, just my two cents.
I agree with your interpretation and think opportunist, with only one stress, would apply to both red dice rolls from one attack. This is supported by the real world functionality of a cluster missile, the spending of one target lock, and the fact that both dice rolls have to miss to trigger munitions failsafe. These indicate that one attack triggers two rolls of the red dice, which is a cleaner way to think about it. You treat it like two attacks even though it is one attack with two opposed rolls.
From the cluster missile FAQ:
"If a ship is equipped with Cluster Missiles and Munitions Failsafe, both attacks must miss for Munitions Failsafe to activate."
If it was truly two attacks, rather than one with two opposed rolls, then munitions failsafe should have saved that second half of the missile card for you.