When creating new forms in Gravity Forms, I used to have the problem where fields would double up. For example, if I added a Phone field and an Email field, Gravity forms would add two Phone fields and it would be impossible to edit the second field. When creating big forms, this became quite a hassle.
The way I fixed this was to simply slow down when creating the forms. I used to click all of the field buttons that I needed in rapid succession. It appears that this is what creates this problem.
Therefore, when creating a form, add a field such as Name. Wait about 5 seconds after it has been added and then add the next field. This should solve the problem.