So rare that most reference books don't mention it: a twin filler 450 Desmo, built in 1969. Some had a decompressor and some didn't and along with the 350 (there's a love-fest in Benzina#6) the twin filler fuel tank quickly became a single filler. Ducati don't even have records of this era, but only a few hundred of the 350s were made, and far less 450s. They make a roundcase 750SS look common, and the fact the fakers have left them alone tells how rare they are.
Yet you can own one - £16,000 from Made in Italy Motorcycles. With the far more commonplace Tartarini-styled yellow-peril 450 Desmo making £10k, (799 built) that almost looks reasonable