Other GPS vendors often note this feature on their promo materials. I have not seen any mention of multipath on the Emlid site. Does the RS2/M2 have any features to lessen multipath interference?
Both Reach RS2 and Reach M2 can suppress some interference on hardware and software levels, however, the efficiency depends on the environment. As well as other RTK GNSS receivers, Reach devices work the best way en environment with a clear view of the sky and without objects that can cause interference even if they are able to handle some of them.