I don't think the one who agreed to a two hand session should have done so unless they were confident that they could follow through. Reading the ad, I get the sense that one of them may be the more established and possibly trained therapist (and not the one you were trying to schedule) so if the other one is less experienced that may be another reason he (or the partner) was unwilling to go forward with you solo.
I have had some good luck with 4 hands - they are definitely pricey so not the norm, but in almost every case I have found both of the masseurs focused appropriately on me and my experience.