As I see a question here I'll answer this one - It was one quake - 2 different magnitude scales.

If you look at this page about the quake:
http://wwwneic.cr.usgs.gov/neis/qed/20010101065704.HTML

You will see it listed as 6.4mb and 7.2mw - both are different methods used to measure the energy of the earthquake - refer to this page on magnitudes from USGS:
http://wwwneic.cr.usgs.gov/neis/general/handouts/so_many_magnitudes.html
and this:
http://wwwneic.cr.usgs.gov/neis/general/handouts/magnitude_intensity.html

Canie