External chat not merging even after adding the contact?

I was chatting with an external contact but after a week later that's when I added that contact.

It opened a new chat window after he accepted. Shouldn't it merge or continue with the original chat? Why can't I merge it? It's showing 2 same names in my Recents. One with his profile picture in it and one with no picture.  I want to keep the original chat but I also want to see his online status which I can't see in the original chat.

Is there a way to merge it in just one chat?