Hi:
This can all be accomplished using your OBiTALK account's dashboard. I'm not going to post screenshots again, but here's a summary, assuming starting from scratch -- if you have already successfully set up both Google Voice accounts to work on the 202, then skip those steps.
Log onto Google Voice account #1 in a web browser. Open a new tab in the browser (Ctrl-T). Log onto the other Google Voice account. Open another new tab in the browser.
Log onto your OBiTALK account. Click your device to get to the next page, allowing you to configure its Service Providers (SP1 -- SP4). Click on SP1. Follow the steps to configure Google Voice. When you do so, OBiTALK will send you to your Google Voice account via a pop-up window, asking your permission to allow OBiTALK to access the service on your Google account. Look carefully at the Gooogle/Gmail/GV user name that it displays, and pick the one you want to use. Complete the setup. Note that there is a bug that causes OBiTALK to display the in-progress "configuring" spinner indefinitely. Wait a few minutes for the LEDs on your OBi to stop blinking, then refresh the web page to confirm it's finished.
Now, click on SP2, and configure Google Voice. Carefully read the pop-up and select the other Google Voice user name.
After this is working, you now have GV1 on SP1 and GV2 on SP2. You can now click on the SPs again, and select which line to use as primary, and which of the two phone jacks to use for inbound or outbound calling.