The AV901WPIY (with 3 RCA jacks for all inputs) is designed for installations that have a need for separate audio channels. For example, some VCRs and Video Cameras have video plus stereo outputs available on three RCA jacks. The AV901WP can run these signals using three of the four pairs in standard UTP cable.
You get the same high quality baluns with the addition of an enhanced appearance of wall plates, giving you a neater professional installation.