dual sim router to fortigate

Hello,

I have a Cradlepoint with dual sims that I would like to VPN into my foritinet 100D.  I have it working perfectly for the first sim.  I am wondering if I can have the second sim use the same VPN connection as the primary sim?  Each sim has a different static IPv4 address.  The reason for the 2 sims is Verizon throttles us after 25GB.  I am going to setup the Cradlepoint to switch sims once the primary reaches 24.75GB.  Based upon setting up the first VPN I would guess no as I can't enter the two different IPv4 address of the sims in to the VPN config.  What is the best practice for dual sim setups?

Thanks,