For VC6, it's actually msdev.com (the VC6 command-line compiler, which the action calls to actually build a project) that determines which configurations to build. In our tests, multiple configurations are built only if the full name is not specified (i.e., Win32 Release matches only Win32 Release, Win32 Release Bob matches only Win32 Release Bob, while Release matches both).
http://www.kinook.com/VisBuildPro/Ma...projecttab.htm
For VC7 and later, the Make VS.NET action itself does implement matching of configurations, and specifying a configuration of 'Win32 Release' will match only that configuration and not one named 'Win32 Release Bob'. Specifying a regular expression like 'Win32 Release.*' would match both configurations.
http://www.kinook.com/VisBuildPro/Ma...olutiontab.htm