Mentioned only by Adlung, who says:

Dunecken 2', according to Praetorius, is to be found in the Marienkirche organ at Danzig; I do not know, however, what it actually is. As far as I can see, it must be an Oktave stop, since it is indicated as a 2'. But it might be a stopped register, or a reed -- I cannot say.

Bibliography