I made an interstate purchase in the month of september 2013.The bill bears invoice date as 21/09/13.I entered this bill in annexure IA of september 13 vat returns.But by mistake i again entered the same bill but with invoice date 01/10/13 in october 13 vat return.In both the month's return ,the invoice no.& all other details are same except the date.The c form has also been generated online for the both the month. Please guide me how can i cancel /rectify the entry made by mistake in oct 13 return and what to do with the extra c form of oct13 ???