Neverending 你好 exchange, is it normal? When should exchanges of the phrase "你好" end? I regularly see a Chinese person who greets me with "你好." If I respond with "你好" he immediately says "你好", and so on.  I normally end it with "Yes, I'm fine." in English.  Am I doing something wrong?
This does happen every now and then. It is just a way of expressing enthusiasm to see you.

And from experience it won't go on forever, usually just a second time, but sometimes people will say "你好, 你好" or even "你好, 你好, 你好" in a row.

Think of it as a handshake, it is not going to go on until it is awkward, just showing some enthusiasm with a couple of extra "hello's".

I would suggest going to the next part of the conversation with something like "你好吗?" or "你怎么样呀？". If you continue on with English with "Yes, I'm fine." this may be like dropping a handshake in the middle.