Windows installer appears to package a 32-bit build as if it is a 64-bit build

The qt-project Windows binary installer installs both 32-bit and 64-bit builds in Desktop\Qt\5.0.0\msvc2010 and Desktop\Qt\5.0.0\msvc2010_64. Examining the .dll and .lib files in the directories shows that both builds appear to be identical, while for the corresponding Digia-generated Windows installer the libraries are significantly different in size.