I mix different inks. I have never mixed Rose Cyclamen though, as I really like it as a summery ink just the way it is. IMHO you are probably safer to mix 2 inks from one manufacturer than 2 from different manufacturers. Others will disagree on that though.
On the other hand check out Richard Binder's burgundy ink mix that's equal amounts of Waterman purple and Sheaffer Skrip red. That works.
I would try mixing a very small amount first just to see how it goes.
If you're planning on adding black, to your RC, then you will usually only need the tiniest speck to change a shade like this dramatically