Cubase 6 and Cubase Essential 5

I start on my computer with C5 Ess and after 6 month I install C6. Can both C can be on same computer or can I expect problems. So far C6 works ok. After I buy CC121 I already instal C5 AI but then I unstall it.
Are this actions some have make troubles? Or simper Q: Can be more version of Cubase on same computer?

yeah i’ve got 5 & 6 installed on my pc.