I have (on a shelf) a Moroso dual head filter head. The
oil goes through in parallel - that is, the
oil goes into both filters at the same time, not into one filter then out and into the next one....
Pros - double the filter area
Cons - I have found on an FE in an ERA engine compartment, there is no space for the dual filter setup if you want to mount it in the "correct" location - top left of engine.