The sisters were Michelle and Lisa Gabriel.
I quick IAFD search shows that they were both in a few movies together:
http://www.iafd.com/together2.asp?perfid1=mgabriel&gender1=f&PerfID2=LGabriel&gender2=F&together=0
I remember a scene at the College Invasion website a couple years ago where Tony Pounds was with an amateur girl named Sunshine. She was a cute blonde and was wearing a blueish/purple shirt through most of the scene. I remember she made Tony cum twice. Does anyone know which College Invasion...