AMENDMENT IN GSTR1

I have a query relating to gstr1 b2b section . actually there are 2 invoices under b2b but my accountant made some mistake due to which each invoice value in b2b tab gets doubled . the taxable value, cgst ,utgst and total values gets doubled. this happened in the both invoices , due to which the tax amount also gets doubled. .this happens in sep gstr1  2019 which has been filed. i found this mistake later when my party showed me the invoices in its gstr2a .now what should I do to rectify this.