Presumption as to documents shifts initial burden to accused for proving falsity and authenticity before admission. When a document produced under the Act, seized from a person's custody or control, or received from abroad is tendered by the prosecution against an accused, the court shall, unless the contrary is proved by the accused, presume the truth of the document's contents and the authenticity of signatures and handwriting; and shall admit the document in evidence even if it is not duly stamped, provided it is otherwise admissible.