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One Route Next Hop

In this scenario, because CE-1 and CE-2 are connected to a single router, the packets coming through the WAN interface of CE1 cannot be in the same subnet of packets coming from CE-2. In such a scenario, NAT must be enabled.
ha-group-next-hop-to.png

Router Is Two Hops

There is no issues for this scenario.
ha-group-two-hop-top.png