Yes two works best, if you were going to do 4 I'd imagine they would need to be at least 3' apart from each other.  IF it is a 4 or 5 wire fence 2 at a time work perfect.  We just have a 3' axle with two pegs of rebar on each end with some flat round steel on bottom to hold the rolls, spray them with WD40 to keep them spinning nice and easy.  Tongue is just long enough that you can keep a tailgate down and not hit the wire with it.  It's unrolled many many miles of fence 1/4 at a time.