Because Markus can't put every sound in a Mark VI and can't make realistic Chamberlin sounds that way.
In a message dated 1/21/2011 4:23:29 P.M. Eastern Standard Time, tomdcour@amnh.org writes:
I wonder why he would do that, the samples he provided for Nord were
made using a Mk VI
> If so, that would seem to explain some of the EQ differenced noted by
> Berington.