Is there any way to diagnose whether a Cam Senor problem originates with the Exhaust or the Intake?

Someone posted on this forum that the sensors are the same, I guess it is worth replacing one then testing and if that doesn't work swap with the other. Odds are only one is bad.

What is strange is the car is running what seems to be perfectly, no symptoms of a problem.

It was also posted on this forum to use only the OEM cam sensor because the aftermarket was unreliable. What is the best source for OEM parts, can anyone recommend a good OEM Internet dealer?