No mystery, my friend, just a typo by the original seller in the craiglist and later ebay listing. The bike you mention is a 2000 model, not a 2002. I verified that with the serial number code before I bought it, for a very reasonable price off ebay. The 'mystery' is resolved in the thread below
YB11 and a question
Short version is that they were built as part of the original YB11 run, and simply painted up in this scheme and with the 25th Anni logo and numbering on the triple clamp as ordered. All the US models came in as part of a single container load by the last Bimota distributor, Bob Smith at Motopoint, and are all "2000" model year according to the year code on the 17 digit VIN. There were models from Europe with 1999 and 2000 VINs.
Were there 50? According to what I have been told, the actual number was far less. The triple clamps were made up and when a bike was ordered, they were put together, painted up in this paint scheme rather than the normal red and black and then sent off to the dealer/distributor for sale. That means that my bike, #4, was put together after the only other one I have seen, #40. Total production? Less than 20 and potentially less than 10. Difference from a 'normal' YB11? Logo on triple clamp and paint and decals only.
Dave