How to check same item repetition in report

Hi All,

I have created report for customer enquiry from Enquiry & Enquiry Line tables and i am showing stock from item card in this report,

if one item entered more than 2 times than stock also repeating same no of times as per below details:-

but i want to display stock for one time only in first line and after this all should be zero as per below image:-

Pls tell me how i can check & set to zero same item's stk repeating more than one time.

I will be very thankful to you.

Neel