The possession of two or more of any single article that is obscene material or child pornography, or the possession of a combined total of any five articles that are obscene material or child pornography (except the possession of them for the purpose of return to the person from whom received) shall create a presumption that they are intended for sale or commercial distribution, exhibition or gift, but such presumption shall be rebuttable. The burden of proof that their possession is for the purpose of return to the person from whom received shall be on the possessor.