Related thread from just a few months back. DIY type deal, but to find a set of duplex dupree pumps is quite challenging! I have an add which showed them in simplex, duplex and triplex configurations! I've seen hundreds of simplex ones, three duplex ones actually in the flesh and never seen a triplex in person.
https://www.yenko.net/ubbthreads/showflat...true#Post418790