hi,
look at these posts and comments
blogs.msdn.com/.../how-to-have-few-microsoft-dynamics-nav-2013-services-on-the-same-server.aspx
Installing NAV 2013 with different builds on same server.
www.advanced-business-systems.com/.../Installing-NAV-2013-with-different-builds-on-same-server.aspx
you can have only debug problem using debug with different builds i think