I've had maybe 5 teams this week submit picks using a superstar they already picked. One team picked a driver they used only 2 races ago! Check your driver stat sheets each week if you can't remember who you've used. I'm not going to email you to let you know that you have used someone, you'll just be disappointed once you realize you didn't get double the points for a driver you picked again.
personally, i just write who i use each week on a 3x5 card and leave it next to my moniter, that way there is no confusion and i dont have to keep looking on the stat page to confirm who i've used.