If you are an admin, then only you can allow one Dropbox per computer. To allow only one Dropbox per computer, login to your Dropbox account and click 'Admin Console' tab. You will see the 'Authentication' tab. Check the box which says 'Allow only one Dropbox account per computer'. If you do this, team members will access only one Dropbox account. But they will still be able to acess both accounts via website and the Dropbox mobile app.