There are two parts; the d-pickup roller and the separation pad. The separation pad is a little felt-feeling pad that sits under the d-pickup roller.
Other things you can try:
1) Fan the paper first; static on the paper if you are in a dry office can cause this. Try a humidifier in the same room as the printer if it is dry.
2) Turn the paper over. I know it sounds silly, but it can make a difference.
3) Try different paper. If it does not have a clean cut, and edges are sticking together, it will pull multiple pages. Step 1 should eliminate this, however, if you fan it well first.
Hope this helps!
Just my $.02
"In order to start solving a problem, one must first identify it's owner." --Me
--Greg