
In the following episode Blood Bonds once again towards the end Cat is bemused to see Supergirl and Kara meet right in front of her. This causes her to admit she was wrong to think they were one and the same.
Fast forward to the last episode of season 2 and we found out Cat knows Kara is Supergirl.

So was Cat really duped by this act of Kara playing Kara Danvers and J'onn playing Supergirl but at some point something set off her original suspicions or was she playing along the whole time?
Thought I'd ask this now since those episodes have been discussed in the replay of season 1 thread, although this question may be a bit premature since there are of course other episodes from season 1 yet to be discussed that may affect your answer if your participating in that thread.