Team 302 has been building two robots for the past two years. In fact, the only year we didn't build two was our rookie season in 2001. My suggestion for building two robots is such - Rookies don't and non-rookies do. Simple as that. Rookies have far too much to learn and building one robot is a feat, let alone two! Non-rookie teams have "been around the block" before, so I would think building two is not out of range (financial resources is a whole other issue).
Raul: I found it very interesting that 111 makes the prototype robot into the second robot. 302 builds two identical machines, which means that we have to have our final design ready to go and then fabricate like heck! Some would say that this is inefficient, but I vehemently deny that. We take our 2nd robot to all competitions (yes, Nationals too), which allows us to have spare parts - we just happen to have a spare part of everything. I like the idea of using the prototype robot as the second robot, but we typically build our proto's (for short) out of wood to save on some costs. What I like about Raul's philosophy is that it is a time saver because you don't have to have two exact alike machines, but I also see the benefits in going the extra mile to create a spare part of everything.
Just a note... my next comment is not meant to be bragging, but to make a point:
In 2002, we were even modular enough to swap out frames, if need be, because the two machines were exact twins. Reminder: Beatty nearly lost the National Title because SPAM (180) broke their frame in the second Championship match (out of three total matches).
I know swapping frames is a quite a stretch! But my point is that having two exact machines (as long as they are modular) allows you several advantages - all of which Raul all ready noted.
The only negative or disadvantage to building two machines is.... "Where the heck to put these things?" (post-season comment made by our team's project leader).
We actually now hang the robots from the ceiling of our machine shop - a reminder of what hard work buys.
Good luck everyone this season. I truly believe that this year's game will be the most exciting and competitive game that FIRST has presented. As the old adage goes: "2 bots are better than 1" (or something like that)