Doesn't work that way.
When you use multiple keys,all lines will have a different UA,so,it will decrypt each and everyone of them.
It will only update the key for the first one,the rest will remain saved in oscam_emmUnique ( I think that's the name),oscam will never overwrite with the same key.
So, if the first one is an invalid/expired UA, it will never attempt or try the second one?