一式两份，有正副本
If a form is in duplicate, an exact copy has been made of it.
The application has to be completed in duplicate. 申请表格必须填写一式两份。
They will send a draft contract in duplicate.
Please fill these forms out in duplicate and file the top copy of each with our office.
They exchanged signatures on a document written in duplicate.
We need to submit documents in duplicate with original signatures.
See also: duplicate noun