Nope... this is a 100% authentic R&M Birdy Yellow. There are a few (very few) threads here on BikeForums about putting 20 inch wheels on a Birdy.

I also noticed that you posted a similar message to the Birdy Yahoo Group. In that Yahoo Group, you'll also find information about 20 inch wheels on a Birdy if you do some searches.

(Hopefully this weekend) I will post up a thread about the mods I've done to my Birdy bike. Up-sizing to 20 inch wheels allowed me to learn a lot about my Birdy and how the new, older, and VERY old models of the Birdy differ.

Besides buying new wheels, to up-size from 18 to 20 inches, the other immediate adjustment you will need to make are brake adjustments in the front and rear. There are adapters you can buy that allow you to use regulat V brakes, however, there are some v brakes that do not require an adapter (but can be too costly to some... like me!).

I'm at work right now, so I can't get into too much detail, but I'll be sure to post up a thread this weekend detailing my Birdy modifications.