I found some more info on the authentic 959 Speedster:
In 1987, Porsche delivered a Porsche 959 to German race driver Jürgen Lässig; who, owned the car up until he had an accident on the Autobahn in 1988. The 959 had flipped over and was severely damaged in the collision with an Audi 80 on the A 81 at Singen on the top, right front and on the side. From there it was bought by a company called Auto Becker. The damaged car went to Auto Becker in Dusseldorf where it was converted to convertible. The engine technology and the complete electronics remained untouched; Stiffeners were welded in. Becker chopped the roof off and fit a 911 Speedster windshield. They also fit a folding soft-top. Afterwards, the 959 Speedster was shown at the IAA show in Frankfurt. A collector from the US bought the car for allegedly 3 million D-Mark. The car can also be converted at any time to a normal Cabriolet, or hard-top configuration. Becker preserved the original roof to be installed if so desired as a removable hard-top - by way of a few handles and the exchange of windscreen and hood. This original style roof was supplied in a very large custom made padded box. The 959 Speedster was tested by Sports Car International in February 1992. From the waistline down the car looks like the original 959 which it is. From the waistline up the 959 in Speedster mode looks like a 911 Speedster.