Win 8 embedded key

My existing main win 7 HDD (#1) was cloned to another Win 7 HDD (#2). My objective is to install/upgrade Win 8 to the clone #2 to try out, yet still have the option to re-connect Win 7 #1 (only) on the same mobo. Question, if I install win 8 on clone #2, the product key apparently is embedded in the bios-hardware. Once win 8 is installed, can I re-connect win 7 #1 and boot up, or will the embedded Win 8 product key prevent this or create issues?

MS support is ambiguos and tells me sure you can, but the explanations appear uncertain. Anyone have a clue about this issue?

Thank you,
Washton

 

I did the same thing but since I had some errors with win7 (nothing serious) I used my win 7 recovery disks and installed it without any updates or extra software on a new hdd and then used the win 8 upgrade. No problems. I go back and forth between hdd and no issues. I even did it with a third hdd but there was some physical errors with it and I discarded it but it installed just fine with no problems.