Should be no surprise, when software is installed a file association is created that links its special file extension with Windows. This allows you/me to double click on a file to open it with the correct application.
Revit versions don't distinguish themselves with a special executable file for Windows to recognize them as different, they are all just "Revit.exe". This means that Revit Architecture, Structure and MEP are the "same" when Windows sees a .rvt file (or .rfa, .rte and .rft).
Having more than one version of Revit (RAC,RST and RME) and/or having more than one release 2010, 2011 or 2012 for example is a recipe for problems. When you install just Revit Architecture, no problem. If you install a newer version Windows thinks the newer version is the "one". Double click on a 2011 file now and you'll likely be opening it with 2012 instead. If you install RAC first and then RST Windows will think every project is a RST file. It all boils down to wasting your time waiting for a file to open with the wrong version of software and having to do it over again.
Simple, don't be a "double clicker"!
Revit versions don't distinguish themselves with a special executable file for Windows to recognize them as different, they are all just "Revit.exe". This means that Revit Architecture, Structure and MEP are the "same" when Windows sees a .rvt file (or .rfa, .rte and .rft).
Having more than one version of Revit (RAC,RST and RME) and/or having more than one release 2010, 2011 or 2012 for example is a recipe for problems. When you install just Revit Architecture, no problem. If you install a newer version Windows thinks the newer version is the "one". Double click on a 2011 file now and you'll likely be opening it with 2012 instead. If you install RAC first and then RST Windows will think every project is a RST file. It all boils down to wasting your time waiting for a file to open with the wrong version of software and having to do it over again.
Simple, don't be a "double clicker"!
