Hello Tejas
The RD for a certain VRF does not need to be the same across all of the MPLS domain. The RT will be used to import and export prefixes between VRFs on different PEs.
I believe that this Cisco community thread quite clearly explains it:
Specifically, it states:
MP-BGP exchanges the VPNv4 (RD:IPv4) prefixes between the PEs (P routers are not VPNv4 aware) not IPv4 routes - When a PE receives a VPNv4 route it discards the RD attached to it and attaches its local RD (according to the VRF that the route is going to be injected into according to the attached RT and the local VRFs import RT) - Since for the local router routing table database the VRF is identified via the RD prepended to the IPv4 route to construct the VPNv4 routes.
I hope this has been helpful!
Laz