My File Upload field keeps adding a '1' to the assigned Field Name for Script value string.

My File Upload field keeps adding a '1' to the assigned Field Name for Script value string.

Hi, I am designing a form that has 10 File Upload fields. 1- 9 is fine, but for the 10th upload field, the system keeps adding a number '1' to the Field Name for Script box under Options. Is this a bug? Why is that?