I agree with Saucepan Man (who doesn't? :D ) in that going many places gave Aragorn his many names, not necessarily hiding from the law.

I have moved over 15 times in my life, so I meet hundreds of thousands of people, (really, I do) and all these people give me different names; here's a few:

Fred
William wallace
wierdo(I'm still called this one)
Brian Boru
Robert Bruce
Bob
Billy-Bob
...

The list goes on with the more people I meet.

Does anyone else get multiple names, like Aragorn?

Building on what Saucepan said about Aragorn's need to be incognito, I think that he had so many names because he kept getting recognized as a noble lord, no matter what he did. The hobbits saw it in him, and certainly Denethor did. It seems that Aragorn's drawn to nobleness like a moth to flame...
So anyway, as soon as one name became recognized as a 'noble lord', he had to become someone else because he couldn't risk them dwelling on that line of thinking too long. This seems to be the especially the case with 'Thorongil' and 'Strider'.