If you mean can two people work on the same RapidWeaver project file at the same time, then no. There are ways to work on the same site at different times.
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Store a project file on Dropbox. But, if you do that, follow these rules on this forum post
Storing Rapidweaver sites on Dropbox
You can also now store themes and addons (plugins and stacks) on a service like dropbox and I believe iCloud. -
RapidWeaver has many CMS stacks now that you can setup a website, publish it and then anyone you give access to can adjust content. My favorite (of course because I work for Joe Workman) is Joe’s Total CMS but there is also Easy CMS (by Joe), Armadillo (by Nimblehost), Pulse CMS and others out there too.
I am sure others will come up with other ideas as well.