When adding the 1st Google Voice account (to SP1), in the Configuration box, checkmark boxes for all Phone 1 for outbound and incoming. Phone 1 is for Phone 1 port.
Do the same when adding your 2nd Google Voice account (to SP2), be sure to check boxes all for Phone 2, Phone 2 is for Phone 2 Port.
And remember that the OBi202 Phone 1 port has 4 active wire and for 2-LINE phone only. While Phone 2 port has a single active pair for SINGLE-LINE phone connections.