Dual Boot OSX on Retina MBP 15 I want to install a fresh copy of OSX onto my Retina MBP, next to the one that it came preinstalled with.  

I have created a 2nd partition using Disk Utility ready for the install, but have now found out that i have to do 'internet recovery' just to get a copy of Mountain Lion onto my machine.

Just to be clear - i dont want to backup using Time Machine then restore onto a new installation.  I just want a clean, fresh installation of Mountain Lion, separate from my current one.

Can 'Internet Recovery' install to a 2nd partition? or would it hose my default one in the process?

By using Disk Utility to re-partition the SSD, have i blown away the recovery partition that is apparently hidden away on the disk when it comes out of the factory? (when i hold down the option key on boot, it gives me the option to boot into recovery so i assume its still there?)

What is the best way to create a fresh copy of OSX alongside the default one?

If have read that the App Store Mountain Lion is different from the pre-installed Retina one - is this still the case?  and if i did download it, would i have to pay for it?
The best way is to boot into your current OS X install, and download the Mountain Lion installer from the Mac App Store. When the installer asks which drive to install to, select your second partition.



Internet Recovery is different to the Recovery HD partition.

Generally…


  As long as you have a valid Recovery HD partition, trying to boot into Internet Recovery will instead boot your Mac into standard recovery mode.


Both recovery modes download OS X anyway…


  installing Mountain Lion from within recovery mode requires an Internet connection to download the actual OS.


…so I recommend using the Mac App Store to install Mountain Lion as I mentioned above.



Disk Utility shouldn't let you remove the Recovery HD partition unless you are in Debug mode. It is unlikely that you have accidentally deleted the Recovery HD partition, and since you can select it when holding alt to select a boot drive, I doubt very much that it's gone.



The App Store Mountain Lion installer is the universal installer capable of installing on any compatible Mac. There is no 'different installer' for Retina or otherwise.