Stick with getting an SW44, then run a second line to the Dual Tuner and 1 line to each of the other receivers.
I think "Installer' is mixing DP with DPP, to the besk of my knowledge there is no such animal as a DPP34, that would be a DP34, this would also require you to run 2 lines to the Dual Tuner, so no advantage in using it.
A DPP Twin LNBF, feeding a DPP44, give 4 outputs, allcapable of feeding a Dual Tuner Receiver with the addition of a DPP Separator, the DPP33, can feed 3 of them.
As I said, you already have the Legacy LNBF's, just get an SW44, feed it with 2 lines from each LNBF and run extra lines for your receivers, lots of them around for $50, new and boxed.