Channel Tools ?

 
Just working out how channel tools works so thought i would do some hands on experiments so it sinks in properly.
Just wondering why the waveform is upside down ?
 
1) I recorded a track ( record 11 ) then placed channel tools on this track to separate the signal to the left side> see picture
2)Then i recorded the left side to a new aux track ( record 18 ) and the waveform when you look really close is upside down
 
it is no problem because when i flip the phase switch on record 18 everything cancels out which means its an identical copy > though i am still curious why its upside down > i got a feeling this may be normal procedure can anyone elaborate .
 

Thanks Scook