when i run two receivers on the same antenna i most often get more aircrafts when both streams are combined. i leveled both receivers not perfect but really pretty well - and of course there are differences in the sdr-dongles as well as in the incoming signals.
but because the pi2 and pi3 are multicore computers couldn’t be there a slight improvement if two instances of dump1090 would examine the same incoming data-stream from a single dongle - and this way together find more messages/aircrafts than one instance?
cheers
tom