Looks like kinship targets the first mob in the room with the same keyword rather than the exact mob itself.

kinship 3.dwarf trade flail for axe
You discuss your kinship with the dwarven guard for a while before offering him a trade.
You convince the dwarven guard to part with an axe with a blade of opal.
You give a flail of crimson stone named "Dragon's Heart" to Old Twarak.

While Old Twarak was appreciative, your weapon will now be given to the right dwarf.