Hello Denise,
I would suggest you to use different RDs because in this way you can have :
a) both PE's advertisements propagated by RR servers to all PE : faster convergence
b) if enabling in VRF eiBGP multipath and IGP cost to PE is the same a remote PE can even install both advertisements and you have flow based load-balancing for MPLS VPN traffic
note: What needs to be the same in a any-to-any VPN is the route-target that is used to decide what vpnv4 prefixes are to be imported in a VRF.
Hope to help
Giuseppe