the two grooves on the other side are just more grooves used for the same task
it is very possible the they could have been used for sharpening bone awls also
other uses can be for shaping bone game pieces and ornaments
if you look at 7th image on neogeo's post it shows how the abraders were used
here is the link;
http://www.treasurenet.com/forums/american-indian-artifacts/296360-yardsale-score.html