Hi,
RUTX12 will not aggregate two links, or in this case two modems. The main uses of two modems in RUTX12 are traffic splitting, load balancing between two active mobile connections, and seamless failover.
So, unfortunately, you will only see a slight increase in speed, which is like MAX 5-10Mbps increase when using load balancing, but you can't aggregate two modems to work like 1+1=2mbps.
EB.