phplib authentication questions

I use phplib's session management and authentication. Adding my own info into it where necessary. So, it does ask to login when appropriate. However, every once in a while, I get errors in insert. Its an error in the table with a duplicate entry. Its trying to insert a record that is already there with a primary key. I could remove the key, but i think that it should stay there as is, and I should figure out why, from page to page, I will get the same data trying to be inserted. I am wondering if anyone else is having these issues with the session stuff. thanks.