triplicate
/ˈtrɪplɪkət; `trɪpləkɪt/ n
(idm 习语) in triplicate consisting of three identical copies, of which one is the original 一式三份（其中一份为正本）
submit an application in triplicate 提交一式三份的申请书.
triplicate / ˈtrɪplɪkeɪt; `trɪpləˌket/ v [Tn]
copy (sth) so that there are three copies including the original 把（某物）制成一式三份（包括正本）.