one of three identical items, esp. copies of typewritten material.

to make threefold; triple.

to make in triplicate

to triplicate a report before releasing it.

produced in or consisting of three copies or parts; threefold; triple

triplicate contracts.

in triplicate

in three identical copies

This letter should be done in triplicate.

threefold

That goes for me, too, in triplicate.