What image version ?
We had an issue for a similar case (the class /instance variable names
were copied *and* renamed too)
yes I faced this problem it was really strange :)
18957
<https://pharo.fogbugz.com/f/cases/18957/Class-copy-should-not-change-the-name-of-the-instance-variables>
Class copy should not change the name of the instance variables
This was fixed n 60189
(actually, with this change, the pool dictionary definition is just
*not* copied but empty, hm, but I think this is better
than creating a new with the changed name).
