That's interesting, because Tripoli (Lebanon) is a mainly Sunni Muslim city. The name is clearly non-sectarian.
There is a list of Tripolitan family names here -
http://www.tripoli-city.org/people.html#NNasr and Nasser are listed, but not Nassar. I believe the spelling Nasser is stressed on the first syllable, Nassar on the second, so likely to be different names with similar meaning.