Not sure about contradictory? I'll assume the clean install is over the 'legal' W7 which is read by the install before the process starts. Keeping the old W7 and doing a NEW install to a clean partition IS NOT supported. The bottom line, you can't keep the old W7 around.
Dual boot options
I just bought a Windows 7 machine and purchased the $14.95 Windows 8 upgrade. Can I keep my Windows 7 running and install Windows 8 on a second partition or in a virtual machine. The "Upgrade Assistant" looks for an existing OS so I could not figure out a way to do that easy.
Technically, no, that is a violation of the license agreement. The upgrade replaces the old license completely. The terms are written in very clear language:
The software covered by this agreement is an upgrade to your existing operating system software, so the upgrade replaces the original software that you are upgrading. You do not retain any rights to the original software after you have upgraded and you may not continue to use it or transfer it in any way.
Seems CLEAR to me.... and the only mention of CLEAN was here (and in a comment that wasn't to 'clear')
How do I get to 64 bit from 32 bit Windows?
There is no way to upgrade from a 32-bit copy of Windows to 64-bit, or vice versa. You must backup your data, create bootable media, and do a clean install. After you’re done, you’ll need to reinstall your programs and restore your data.
So I'd say there is no way to do a CLEAN install? I never saw an option to FORMAT during the upgrade, but I didn't boot the upgrade DVD I made either?