A duplicate is a counterpart produced (a) from the same impression as the original; (b) from the same matrix; (c) by means of photography, including enlargements and miniatures; (d) by mechanical or electronic re-recording; (e) by chemical reproduction; or (f) by equivalent techniques that accurately reproduce the original.

Fed. R. Evid. 403 ("Although relevant, evidence may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence.").The so-called undue prejudice rule empowers a trial judge to exclude relevant and probative evidence in order to reduce the risk of prejudice and avert other risks and harms.

United States v. Swan, 486 F.3d 260, 264-265 (7th Cir. 2007) (upholding trial court's admission of agent's testimony as to attorney's statement as an admission of a party by an agent because "the government....A statement by an agent or an employee can be imputed to the principal or the employer (respectively) and be treated as a vicarious admission (that, like other admissions, is exempt from the prohibition against hearsay) only if the statement was made during the agency or employment relationship.

United States v. Mayberry, 540 F.3d 506, 515-516 (6th Cir. 2008) (upholding trial court's admission of police informant's prior sworn statements made during his grand jury testimony as prior inconsistent statements because....A prior inconsistent statement of a witness is admissible, not only to impeach the witness, but also as substantive evidence -- to prove the truth of the matter previously asserted by the witness -- only if the prior consistent statement was made in another proceeding.