usb film scanner problem code 38

I have 2 usb scanners (visioneer 9020 & tamarack 2400FS)If I install only one scanner it works fine, but If I install both device mgr=code 38 “cant load device driver for this hardware because of a previous instance of device driver is still in memory” Using XP have latest Drivers for both scanners. Either scanner works singularly. How do I fix?