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There is only one valve inside oil filters. There may be another valve in the oil system, but not in oil filters. It all depends on the location of the oil filter relative to the rest of the engine and oil circulation system. If such a valve were required, it would be institued within the oil circulation system, not as an extra valve within the oil filter. That way the replaceable oil filter price could be kept to a minimum, while a high quality, life of the vehicle valve would be installed into the car, also making it possible to run aftermarket oil filters.
BTW, if you check out my link, you'll find a similar study (dismantling the filters as well).
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