Partial refund of additional duty

Dear Sir

I have a query regarding the partial refund of SAD.

Is there any provision or circular or notification regarding partial refund of additional duty?As we are selling some quantities of imported goods to our manufacturer customers and pass on the SAD to them and selling the rest quantities to others by charging VAT/Sales tax. We subsequently pay the VAT/Sales Tax to state govt. 

My query is that can I claim refund of partial SAD on quantities sold to the customers from whom we have collected the amount of VAT/sales tax.

Your reply will be highly appreciated.

Thanks.