Hi John,
To turn a shared project file (rpprj) to a standard, single user file, use the 'Export Shared Project to File' (from the 'File' menu)
To turn a standard RP file to a shared project file, open the file, and from the 'Share' menu, use 'Create Shared Project from Current File'
Best,
-Ezra
Disclaimer: I am not an employee of Axure nor am I compensated by the company in any way, shape or form. Rather, I have a vested interest In its continued development as an avid user of the application on a daily-basis. (disclaimer by Ari Feldman)