It refers to a
situation when nothing is absolute or certain
yet, when things are still in the process and one cannot guarantee what the result would be
like.
"I am not sure what is going to happen. It's still a who-who situation."
"I have not
made my mind about this
yet. It's still a who-who situation for me."
"They might be in a who-who situation, let's give them some more time to think."
"You are still in a dilemma?
Wow you are such a who-who"