The Conan pledge manager is open to anyone. Anyone who wants it can sign up for it right now. They don't need to add on to another backer's pledge.
Dormammu is correct. The Conan Kickstarter Pledge Manager is open to anyone that would like to get a Kickstarter version from now until September 25 or 26 thereabouts. There have been discussions about it in forums here, in the Kickstarter comments and on Monoliths Facebook page. Once the Pledge Manager closes you will only be able to buy a retail version of the game so selling or trading a Kickstarter copy will probably be more effective once the game gets released and people have had a chance to play it.