No need to use both.
Bypass filters such as the FS-2500 are actually oil pressure leaks. That is the flow that is passing through the filter is actually "robbed" from the oil galleries feeding the engine lube system and returned to the sump having"bypassed" the main function of the lube system.......lubricating the engine. An orifice is used to control how much gpm flows through and limit the pressure drop in the engine oil pressure.
Extended oil drain on the 7.3 is possible with very specific high quality oil. The increase in cost of the oil and extra filtration system plus the extra filter brings it down the labor savings and the satisfaction of doing it. Used to be standard to have a LF-7500 Lubrefiner bypass filter on all the 318 Detriots, 335 Cummins and 3208 Cats. Rare today. My company has over 5,000 trucks and no bypass filters. We look at costs all the time.....