Q: Can I run 10.10.5 and 10.6.6 so I can keep Netflix current and also run FaceTime from laptop?

I had to upgrade to 10.10.5 to get Netflix to work properly and now I need FaceTime on my laptop, so how do I do this? can I run 10.10.5 and 10.6.6 on the same laptop? Years ago I ran 2 versions of OS X because of having and old print program that only ran on OS X 9 and everything else I ran on 10.4 (whatever) so can I still run 2 OS X versions? and how do you do it?