however vampiric weapon stacks so it may b a posibility but if you really want answers id recomend u try researching it in detail i'd do it but frankly im far too lazy

for a setup id recomend focusing on one character have them lose some hit points then equip a ring or whatever of life and see how much hit points they gain in say 20 minutes game time then put on two rings of life and see how much hp they gain in 20 mins to see if thereis a difference in HP Per Min.