Using track 3 for VCO 2 pitch requires retuning

Starting with VCO 1 & 2 in tune with each other, when I copy a pitch sequence from the pitch track to track 3 or 4, setting them to control pitch I have to retune VCO 2 to be in tune with VCO 1. Not a major issue, more an annoyance, just wondering why that is necessary.