Just as a matter of interest, I have installed Planeplotter and running Flightaware and Planeplotter at the same time, of the same USB Pro stick setup. I am noting though, both observing local data, that the Planeplotter is tracking aircraft a lot further that the view local data link in Flightaware? Why would this be if they are both working off the same data feed? And yes, the planes being plotted are showing up on the normal Flightaware live tracking so they are not false readings.
Planeplotter will feed back plane positions from their network (other feeders) by default. You can turn off the network positions in the planeplotter options.
The PiAware live map is only showing planes that your receiver is seeing.
If you want to see FlightAware world network you have to go to flightaware.com/live
I would not expect any difference between PlanePlotter and dump1090. PP probablly just has different settings for persisting aircraft positions after they are not heard from for a while.