They have 4 arms between them. A Dvati ‘character’ taking the feat has 4 arms. OTOH, of course, if you look at them as separate creatures, neither qualifies. …I’m leaning towards the first interpretation, honestly, but what are your thoughts?
“Would this actually benefit them, anyway?” I hear you asking. Actually, yes. If the ‘main hand’ attack is, for instance, an unarmed strike with the leg, both hands a free for extra attacks courtesy of Multiweapon Fighting.