instead of 3 line items display 6 line items in delivery

Hi,

In ONE sales order there are 3 line items when i create delivery for that sales order there are 3 more line items addedup (Total 6) But those 3 additional item category is TATX. I has checked out the item category and delivery item category determination.everything is perfectly fine.

But problem not yet resolved. What are the possibilities for this issue?

Regards

Ddas