From the helpful folks at Opcode comes this little known fact about the OMS MIDI Time Piece driver: It never ever shows networked interfaces as two icons. It always shows one icon to which you can attach devices on ports 1-17 (17 being a networked standard interface).
Thanks guys! What this means is that if you are using OMS with two MIDI Time Pieces on the same serial port, they will not show up as separate interfaces. Rather, they will show up as one large (16 port) interface. Functionally, this will make no difference to your computer or MIDI system.