Skrivan made a replica, read that Gangl did too. The Skrivan bike is marked on the bottom bracket very plainly, in silver.
Mike Kone wrote of some fakes, way back but that was about all the info I found.
Jim Cunningham at one time stated he had the build cards and would provide an owner a copy, last I knew, that is under reconsideration, an owner would only get it if he had Cyclart do the restoration. Times change.