Divided leadership in a technology driven company

Is it possible to run a start-up with divided leadership ? The company has two partners, Sam and John. Both come from a technology background and both are MS and experienced in almost same domain. Both share a common vision, at the same time both partners want to implement their ideas for making the company a big success.

1-Do you think in such a case dividing the leadership between the two partners can lead to success?

2- If not, then what can be the best way so both the partners can work cooperatively?

Some additional info would be helpful.

1. headcount: are we talking about 5 people or 50?
2. company maturity stage: idea, customer traction, growth
3. company focus: technology marketplace
4. personality traits: is one more outward focused / personable?

Depending of the above information, one could functionally split the work between a CTO and a VP engineering title. But titles are worthless if the company size doesn't support it.

Regardless of the above, Chemistry trumps all - if they work great together, and can respect each others input - then division of labor will occur naturally if they are equally motivated to be successful.

IF there is a problem about who reports to whom and the company is just starting up, you likely have bigger issues then.

Is it possible? Absolutely! As long as there is a good operating agreement, solid division of duties, and process in place to help arbiter/mediate disagreements. There really should be a third person (usually independent with a small share in the company) who will cast a vote that breaks up a stalemate.
As someone who has to mediate founder conflicts, I can't stress enough importance of those items. I have seen nasty lawsuits and broken companies after founder feuds.

P.S. I have deal with "rotating leadership". It was a case of two brothers (equal partners) who rotated CEO spot every 12 months. I probably can write a book about that disaster.

ABSOLUTELY NOT!!!

Look at RIM for perfect example

Your best bet if you can't decide, it to hire someone as CEO, and both of you become VPs, or C-Levels. Say you're good @ Databases, and he's good at coding, make him CTO and yourself CIO; or something along those lines. Problem with co-CEOs is things rarely get done, because even though your ideas are aligned now, they may not be as the company matures.

I think a rotating leadership model (a few years span) will be better.