You can't use plugins from two different accounts on the same computer because you can only be logged in to one account simultaneously.
However, you can use plugins from two accounts simultaneously by authorizing a USB drive for one of the two accounts. Then one of the accounts can be authorized on the computer like usual, and then you can put in the USB drive to use the other account.
If you don't know how to put your authorizations on a USB drive, here's how:
Make sure your USB drive is plugged into your computer. Then, open one of your plugins in your DAW and click the key icon on the bottom right side of the plugin window. An authorization window will pop up. Under the text "Select the device you would like to activate," there is a pulldown menu. Click it and select your USB drive. Make sure the "Activate all my licenses" checkbox is checked. Then click "I'm Online" and enter your login info.
Now you can use those plugin licenses on any computer with a USB drive.