Hi,
If I understand you correctly you want to use two 2 active sim cards at the same time. This is only possible with RUTX12, as it has two modems that work separately from each other and will have two active and totally different interfaces.
If you want to set-up two VPN tunnels from one router - it will be possible with RUT950, but it will use only one internet interface of your choosing: Wired WAN, Wireless, or Mobile.
EB.