I'm testing the install on both 2012 server and 2012 R2 (both RTM) and I couldn't install .net 3.5 without giving the installer two separate sxs folder based on server version. I added a folder sxs\2k12 and sxs\2K12R2 in the prerequisites folder and added code to check for version and use the appropriate folder in the .net install function.
Comments: ** Comment from web user: brianlala **
Comments: ** Comment from web user: brianlala **
You don't actually need to do separate folders. Thanks to the naming of the files, they can all be placed within \sxs with no overwrite/conflict.
Brian