Correct, latest RUT2 firmware versions has improved IPsec, which allows you to use multiple pre-shared keys for different connections.
If you want to establish basic IPsec connection between two Teltonika routers, then all you have to do is configure the following parameters:
- "Remote VPN endpoint"
- "Remote IP address/Subnet mask"
- "Pre-shared Keys" (Press "Add" button in "Pre-shared Keys" section and enter your key in newly appeared line)