Hi,
No, it would not be possible as both mobile interfaces use a MAC address to bridge the modem to the WAN network card.
So this would require two cables and also two WAN network cards to be bridged to, because if it's only one cable and only one network card - bridges will fight over one MAC address to establish the connection.
If you have two WAN ports on your router - then you should be able to route those connections to different LANs.
EB.