At this time, There are but TWO options:
1) Do NOT ever network the two computers...
2) Buy another seat of Combustion...
Combustion does NOT have a "transferable" license like 3ds max... All I can say is that I was told that the license and registration set up for Combustion is more like the one used for Discreet Cleaner, and NOT like the one from 3ds max...
In my humble opinion, I would guess that it probably has a lot to do with the COST of such reg. programs: With the Combustion price drop, Discreet needs to keep their overall products costs down. Remember that 3ds max costs a lot more, and therefore, jusitifies a more secure reg process...
Keep Combustin'
Jack