In my post Why ospf vpnv4 routes look as external route explained that the problem can be overcome by changing the ospf instance id across all instances. But the same can be acheived by changing the domain-id also under ospf vrf instance. In MPLS enviornment the recieving PE will match the packets on the basics of domain id. If the domain id is different then PE thinks the packets are coming from the other domain and treats them as external routes which can be seen at customer end side. So by changing the domain id same on both PE it treats the packets are coming from its own domain and delivers them as inter area routes.