All they happened is some doofus in the past wrote a note in the corner of each document what the the believed date of creation was.
Either they foolishly wrote on the originals, or they wrote on a copy and the copy with the added date was presented as an evidentiary document, which it was also, being government product itself.
Either they foolishly wrote on the originals, or they wrote on a copy and the copy with the added date was presented as an evidentiary document, which it was also, being government product itself.