Same Application

"Same application" refers to two separate installation runs that share the same AppId setting (or if AppId is not set, the same AppName setting), and the same administrative or non administrative install mode, and the same 32-bit or 64-bit install mode*. Two of such installation runs will usually lead to only one actual installation of the files.

(* = This requirement does not apply to any same application information retrieved from the registry in non administrative install mode since the HKEY_CURRENT_USER key is shared between the 32-bit and 64-bit registry. It does however always apply to the uninstall log since the 32-bit and 64-bit uninstall logs are kept separate, even in non administrative install mode. In practice this means you should avoid offering both a 32-bit and a 64-bit non administrative installer to your users without giving these installers different AppId, DefaultDirName, DefaultGroupName, and UninstallDisplayName settings.)

See also:
Side-by-side installation