Dual Boot Yosemite and Sierra on Separate Drives???

Hi Team

I have been a hackintosh user for 2+ years now and have a rock solid Yosemite Build and am reluctant to update my system to 10.12 Sierra. I have now been forced by a piece of software that i use on a day to day basis to run i need to update my system and would like to know if it is possible to have a Dual boot of my original Yosemite on my existing drive and then purchase another drive to install Sierra on is this possible?

What i would also like to know as it has been a few years since i have been through the install process is doing this what are the chance of trying to get Sierra run that i completely ruin my system for the Yosemite Drive or will have the Dual Separate drives eliminate this chance?

Thanks for your time team i really just want another drive to test the install and make sure i can get Sierra running smoothly before i migrate everything over.

Thanks in advance.