what makes fields unique in a form?

what makes fields unique in a form?

I am adding records, by using script in FormX   On Add/On Success script block

I am duplicating records of FormX but modifying a few fields

  1. weeklist = {0, 1, 2, 3, 4};
  2. for each week in weeklist
  3. {
  4.       var = insert into FormX
  5.       [
  6.             EmployeeID = input.EmployeeID
  7.             someField = input.SomeField +1 
  8.       ];
    }


New records are not created and I get the error "Some of the fields are unique"

I did not intentionally make any fields unique. I don't understand why I am getting this error or how to correct it. Please help.