What is the test for prejudicing a defendant on both charges of possession of a firearm with intent to pervert the course of justice?

United States v. Ragghianti, 527 F.2d 586, 588 (9th Cir. 1975). Defendant contends he will be prejudiced by a trial on both counts because the jury will "infer that whatever evidence supports one charge will also support the other." Dckt. 22-1 at p. 9. Specifically, Defendant posits that the government will argue both guns belonged to him, causing the evidence to work as improper "propensity" evidence to convince the jury that because he possessed one firearm, he is more likely to have possessed the other firearm.