Rip again!

Hi, There isnt IMO a way in RIP to identify the source of the RIP packet (the way we have Router ID in OSPF, system ID in ISIS, etc.) Now assume we have 2 vlans defined on an ethernet. Thus we would have two IP interfaces, 1.1.1.1/24 and 2.2.2.2/24 and both using the same physical interface. RIP is running on both these interfaces. My doubt is that how will another router, which is configured in the same way (2 vlans) be able to differentiate between the RIP responses originated by 1.1.1.1 and 2.2.2.2? Thanks, Toms