Look-alikes?

I am not sure how common it is to be told by people that they know someone who looks 'just' like you. It happens very, very often with me. Now, there is apparently a myth that there are 7 people (or is that 9?) in the world who look like any given person.

My earliest recollection is interesting. There was this junior at school (I must have been in the 3rd or 4th grade) who looked a lot like me. He was significantly taller than me, but the facial resemblance was uncanny. There was an instance when I had almost gotten into trouble because of something idiotic this imposter had done! This is also the only instance when I have seen my look-alike.

I have been told many times how I look very similar to someone. This lady's neighbour or that guy's electrician. I have been told that I look like one singer and two small screen actors. Incidentally, my 'look-alike sightings' were significantly higher when I was wearing my hair long.

One day, a friend called me up and excitedly insisted that I reach Koramangala immediately. The reason? He had seen a copy of me. A girl. In fact, he apparently ran into her again a few days later. He swears that she had exactly my face!

The most recent addition - this person apparently is built like me, looks exactly like me and also talks like me. Only he is 80 years old.

So, are there really n number of people who look like us? And if so, does the resemblance go beyond just appearance? How can the resemblance be explained? Is there any connection between look-alikes?

Does this keep happening to me because I have a "generic" face?

---

While I could find nothing worthwhile on the internet, some other interesting stuff I ran into:

http://englishrussia.com/index.php/2009/02/05/russian-lady-killed-look-alikes/
http://haha.nu/amazing/im-not-a-look-a-like/