Help with export value on form field with leading zero

I posted about this issue a while back and was unable to resolve the problem I am having, so I am trying again and hoping for a different outcome.

I am creating a fillable pdf that includes drop-down options for a four-digit name control section on the form. For example, if the last name is Smith the user will enter SMIT in the name control field by choosing each letter separately. Each name control letter will be a separate drop-down field. When the user selects an alpha character from the drop-down list - like "A" - I want the export value to place 01 into another form field. If they choose "B" I want the export value to place a 02 in the other form field and so on until I get to letter J. For some reason, when the export value is a leading zero, it drops the zero off of the form field. Is there something I can do to prevent this from happening? Any guidance would be greatly appreciated.