I tried to connect EM7455 and MC7430 at the same time to Linux PC, they have the same mac address:
owner@CNHKG-EX-001367:~/legato/packages/legato.framework.19.2.0.wp76xx-201906171244/resources/legato$ ifconfig eth2
eth2 Link encap:Ethernet HWaddr 1e:30:3f:37:72:08
BROADCAST NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
owner@CNHKG-EX-001367:~/legato/packages/legato.framework.19.2.0.wp76xx-201906171244/resources/legato$ ifconfig eth1
eth1 Link encap:Ethernet HWaddr 1e:30:3f:37:72:08
BROADCAST NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
Probably this is set via GobiUSBNet.c in GobiNet driver as I saw there is some code related to MAC address.
Perheps you can have a look there.