In today’s implementation of EIGRP, RID’s are advertised to neighbors along with routes. This allows EIGRP to prevent routing loops when redistribution has taken place into other EIGRP processes. Any router that receives a route with its own RID will reject and drop the route.
Unless expressly configured the highest nonshut loopback interface is chosen as the RID. Once chosen the RID is not changed unless EIGRP is reset.