The nickname for those are 'smashed pipe bands' as no one is in tune or time.
PS Re Steam train to mallaig, starts with solo piper, at about 35 secs typically 3 other pipers join in, as the drones come up to pressure they are off tune for a few seconds and you can hear the heterdyne, but by 45 seconds you can't hear it any more - just the harmonies and a little syncopation.