FUI, I have MC17 installed on an XP Pro SP3 machine that has also MC11.1, MC12, MC13, MC14, MC15, MC16, MJ12 and MJ14 installed (i.e. all the newer JRiver program versions that do not need exclusive access to the JRiver sections of the Windows Registry).
There is no fundamental problem with having MC17 and any of the above program versions installed at the same time. Though, apparently something wasn't quite right if uninstalling both versions and reinstalling MC17 fixed the problem.
I guess you could now install a clean MJ14 instance and everything would work just fine. (I am not saying that you should do that. If you want to have two versions for some reason, a better idea would be to install MC16. It works with the MC17 license and contains lots of improvements and fixes that are not present in MC14 or MJ14.)
EDIT
"Clickfree" is a HW backup device brand. A compatibility problem with Clickfree was reported a few weeks ago and announced as fixed in 17.0.26.