Minn. Stat. § 600.08: LETTERPRESS COPIES.

The production of a letterpress copy of any letter, before the officer taking the deposition, shall be equivalent to producing the same at the trial and, when so produced, a copy thereof may be attached to the deposition as an exhibit, and shall be evidence of like force and effect as the letterpress copy itself; but such copies shall not be used if the original letters are produced at the trial.