This has surfaced recently on a well known on-line auction site, a Colnago Master Pui tricycle ,

with two wheels at the front, possibly constructed for stability, or, built for the circus industry?

the original forks are in the background, so the customisation is changeable,

the vendor is asking approximately 2k pounds sterling, but sadly no explanation is written within the listing, or provenance regarding if this was a factory built customisation .

available here