Doepfer

Ok, so I've only had this module for a short while, but I'm having a strange
issue that is more likely me not understanding something than a problem with
the module:

On the cv out for each row, at each step it actually pulses twice for each
"note" in the sequence.  I don't have a scope to verify exactly what it's
doing, but if I pluf the pre or post out into an oscillator, it plays each
step twice (and I'm not using a vca!), I assume it's outputting some sort of
square wave for some reason.  Even when I advance the step manually, for
each step it goes "beep - beep"  (again without any vca)

Am I missing something basic here?  I think I understand the theory of the
155, and I've had lots of other analogue sequencers, and I've never seen
this.

Paul