It seems like it is, but it also seems like it isn't (???)
[[-는 듯 마는 듯하다]]
Discussion on Reddit
From /u/learner-99:

• 밥을 먹은 듯 만 듯하다 = I feel like I don't know whether I ate or not (i.e. I ate too little).
• 친구는 찬성하는 듯 마는 듯하다 = My friend reacts like he's not sure he's for or against it.
• 비가 올 듯 말 듯하다 = It looks like it might rain but then again not quite.