Both my sons were here yesterday afternoon for about and hour. I was talking to the youngest about a road bike build for him if he's interested. At one point he asked which of my road bikes was the lightest. I said I didn't know. So, out comes the scale. We hoisted the three I ride the most up on the hanging scale: Indy Fab Ti CJ; Colnago Master XL; Specialized S-Works Roubaix.
It was unbelievable. All three with pedals, water bottle cages and computers came in at the very same weight. 17.1 lbs. This was quite a surprise to me. But just to make sure the scale wasn't stuck at that level, we weighed my commuter and my old 80s steel road bike. Yep, the scales were accurate. I don't know what the odds are of such a thing, but I'm guessing it doesn't happen all that often, especially since the build is not the same on any of them.