[c-nsp] Distinct MAC addresses for 7609's L3 LAN ports

[Everton da Silva Marques]

Platform is 7609 + Sup720-3B + IOS 12.2(18)SXE4.
Module at slot 2 is WS-X6548-GE-TX.

We have 2 ports of WS-X6548-GE-TX running as L3 (IP)
interfaces and attached to a VLAN of a 2950 switch. One
interface (Gi2/14) belongs to a VRF, the other (Gi2/10) lies
on global context.

However, since the 7609 is advertising a single MAC address
(0014.a9b0.4dc0, from the MSFC) on both L3 LAN ports, the
attached 2950 switch is getting confused.

As work-around, we have manually assigned a distinct MAC
address (0014.a9b0.4dc1) to GigabitEthernet2/10, and it
seems to work properly:

7609#sh ip arp | i -
  Internet a.b.176.1  - 0014.a9b0.4dc1 ARPA GigabitEthernet2/10

7609#sh ip arp vrf PSTN-Gtwy_Access | i -
  Internet a.b.176.2  - 0014.a9b0.4dc0 ARPA GigabitEthernet2/14

The question is: is there any known bad side-effect from
manually assigning MAC addresses onto L3 ports of the
WS-X6548-GE-TX module?  For instance, is there risk to force
(MSFC) software-based forwarding or any similar undesired
behavior?  Please advise.

Many thanks,
Everton