This is always challenging. Sometimes you just have to use trial and error.
I have a sensor facing up on a shelf inside a bento box. You can walk past it all day long and it won’t trigger unless you wave a hand over it (which is what I wanted).
I assume your two doors are 90 degrees to each other?
A lot of people will use masking tape to narrow the field of a motion sensor. If you mask the left side of the one on the right and the right side of the one on the left you may be able to get a trigger point limited to one entry.
You can also do like I did with the bento box: put the sensor on the ceiling, but inside a box or dummy fixture pointing down. This can really narrow the field.
Another option for the bathroom if the door opens in is to put the sensor inside the room behind the door. This will catch the motion of the door from the other side and turn on the light before the door is all the way open.
If you’re willing to set up more devices, you can also use zone detection so each room is controlled by multiple sensors. This can solve the overlapping view problem by paradoxically making the area viewed large enough that the overlap isn’t enough to trigger the other room.but this does require multiple sensors for each room.
@bravenel , @johnconstantelo and others who do a lot with motion sensors may have more ideas.