I asked this question on another site, and the answer was no, except the Royalprint is slightly alkaline and the Rapid fix is slightly acidic. Thus, use a water stop bath.
I have ten gallons of it on hand but have not gotten to it yet, so I can't say definitively. God bless digital: last year I picked up about 20 gallons of Flexicolor fix and Royal print fix for I want to say 10 bucks. The store was going completely digital and they were happy to have the stuff hauled away!
I guess you could test it. Dilute 1+3, fix a test strip, wash it, snip in half, put one half in developer and see what happens. Compare to undeveloped piece.