I have a memif interface with 2 sub-interfaces in different VRFs (fib_id 4 and 5)

If the subnets of the sub-interfaces are different (in my case 10.10.1.0/24 and 10.10.3.0/24) I can send a packet through the second sub-interface and NAT44 correctly creates a session with fib_idx 5 (see attachment trace1.txt)

However, if the subnets of the sub-interfaces are same (10.10.1.0/24) and I send a packet through the second interface, NAT44 creates a session with fib_idx 4 instead of fib_idx 5 (see attachment trace2.txt)

As you can see in the traces, the packet goes out through the correct sub-interface memif1/1.2 in both cases, only the NAT44 session is incorrect