Hi,
The codes are a little confusing some times, because the standard OBDII codes don't always jive with the Volvo factory codes. Bank 1 and Bank 2 normally refer to left and right sides of a V-8, V-6, or other type of engine that has two separate exhaust manifolds, and at least one, sometimes two O2 sensors on each side. Your V70 has two O2 sensors, one upstream and one downstream of the catalytic converter. My guess is that the OBDII reader that you're using is seeing the upstream O2 sensor as Bank 1, and the downstream sensor as Bank 2, or possibly vise versa.

Hope this helps,

Mark