need gst 3b return help. plz help

while filling gst 3b return I made a mistake, 3.1, interstate IGST tax amount RS.4000 supplied to registered dealer, mistakenly shown in 3.2 where we have to show amount of supply made to unregister dealer/person, I mean Rs.4000 tax amount, shown in both 3.1 and 3.2 mistakenly. help me? how to rectify 3.2 part of gst 3b which is actually nill (no supply made to unregister person/dealer)