> That's two stereo tracks in Ardour as I feed
both mono signal
> in the right and left of each track.  Maybe I shouldn't do that. 
There are no rights or wrongs, all that matters is the final outcome.
Though if both tracks have identical data and you don't process them
differently it's probably just a waste of processing power.
     Is there a
receipe in recording techniques that addresses that kind
 of configuration and enables control over the loudness difference
 from a sinle intrument in a single take ?
   Any ideas/suggestions appreciated,
 Cheers. 
 Speaking from theoretical knowledge, wouldn't compression give a more
 even feel to the recording? Of course you'd need to lower your input
 volume to give headroom for the push/pop notes. 
 
Yes, I would say that is the main purpose of a compressor / limiter:
Evening out the extremes in the audio.
/Robert