Only one user changes based will be saved & other 2 will loss their data completely themes from theme options (overwritten behavior or workflow conflict issue). If more than wordpress 1 users working on a site & using theme options. We just found the solution & develop plugin for redux based themes users. This creates lots of options headache during site or theme development lock. If user1 redux is already working locker on theme options & user2 open theme options then his theme options screen will be lock by popup just like wp page/post editor handles this