We suggest avoiding this issue by moving to Account Data Upload instead of Gift Upload.

If you don't mind having gift type AD on the pledge payments but you want to avoid it getting set on the pledge you can consider whether you want to turn off the System Preference "Auto Adjust Pledge on Change of Gift Type": https://www.blackbaud.com/files/support/guides/ta5/Spctv33/Auto_Adjust_Pledge_on_Change_of_Source,_Gift_Type,_or_Overpayment.htm