Yes. The SW44 Replaces the two SW21 Switches you currently have. Instead of each SW21 taking a line from each LNB and then feeding one receiver, the SW44 will take all four lines (two from each LNB) and produce 4 complete outputs. Be aware the SW44 has a power inserter that can be located anywhere along line 1, including right at the receiver.
With the SW44 you still requrie 2 lines to PVR's.
Alternatively you can purchase a Quad DPP LNB. This has a low power consumption switch built in and can supply outputs to 4 receivers. This has no power inserter, will require less cabling, and can run PVRs off one cable if used with a DPP seperator.
You cannot use the DPP44 with Legacy LNBs. You will need to either expand to a second SW44 by splitting the cables before they reach the switches, or to consolidate to one dish and use a DPP Quad head.