Since the 95 is the only OBD I e38 made, it has one sensor just prior to the converters. So your 95 has 2 O2 sensors. All OBD I cars are similar.
On the other hand, OBD II cars have one O2 sensor before and one after each converter. So on all e38s manufactured 96 and later are all OBD II and have 4 O2 sensors.