How are you?

This Abstract's mundanity / blandness is - in my humble opinion - offset to a certain extent by the frequency of occurrence I have witnessed it out there in the Urban world.

The most recent instance was when I was sitting on the bus. The girl in front took a mobile phone call, her opening lines were as follows:

"Hello? Ahhh, hello X, how are you? Yeah, I'm fine thanks, how about you?"

What is the reason for this immediate repetition of the question? Is the first enquiry in actuality just a space filler because "Ahh, hello X" is too terse, followed by the proper question, the response to which is taken on board?

Or is it the case that the second enquiry is automatically tacked on to the answer "I'm fine thanks" because whenever one doesn't get the question in first, it would appear grossly rude to not ask the question back? That is, a double-ask seems a relatively minor indiscretion as compared to no ask at all, with the double-ask being the side-effect of the safety net.

If anyone else has been on the receiving end of this 1-2 before, how have they responded at the second time of asking? I have not always been sure what is best form, because to give the same direct answer a second time kind of highlights the preposterous nature of the conversation up to that point!!