Back in the old days, usernames weren't unique. We had lots of Jenns and Steves and Daves that were all different people. Now, with registration, people are at least guaranteed that their username is unique, and people can click through to their profiles and posting histories to see who is behind each post. But with tens of thousands of registered users, there's bound to be similarities.
There are actually about a dozen variations on SweetPea out there in Chowhound land. You may want to fill out your profile, and choose an avatar that sets you apart from the rest if you're worried that people will confuse you with others.