This is one of probably several responses that will be posted about
this, but yes, the 1970s era "Duo-Arts" were in name only, the "Duo-Art"
trademark having been purchased by (or licensed to) the manufacturer
of those mechanisms, whose name I do not presently recall.

There were, in fact, no other Duo-Art pneumatic components in the piano,
however, it did have an automatic rewind function.  It is undoubtedly
this function that is being triggered by an expression track (perhaps
several) of the customer's 'real' Duo-Art rolls, causing, as designed,
the undesired re-rolling.

The simplest cure, if she wishes to hear these specific performances,
would be to put thin tape over the tracker bar areas corresponding to
the normal Duo-Art expression tracks.  Just don't expect to hear the
dynamic changes you would hear on a properly operating (vintage)
Duo-Art piano.

Oh, and since the rewind function in these Duo-Art wannabes are
typically only on the extreme treble end of the tracker bar, normal
Duo-Art rewind perforations, being on the left side of the roll, will
not cause a rewind when it is really needed, so be prepared to do the
shifting manually.

John Grant