Is it inappropriate for a witness to admit that he or she was not aware of the facts of another witness's testimony?

United States v. Check, supra, 582 F.2d at 675; accord United States v. Ziegler, 583 F.2d 77, 81 & n. 8 (2d Cir.1978). The admission of such hearsay statements is inappropriate where, as in Check, the declarant does not reiterate the statements, for it provides the jury with inadmissible material that it would not otherwise have had. It is also inappropriate where, as in Ziegler, the declarant does so testify, since the hearsay testimony serves to bolster the testimony of the declarant.