I saw a madman with 4 hungry spirits boots and a savage. He wasnt doing well, but he claimed that the four helms gave him a consistent 40%Lifesteal. I figure this was complete bullshit, but hey ive been wrong before
This item contains an Attack Modifier. Attack modifiers are exclusive and do not stack with other attack modifiers.
Lifesteal acts as an attack modifier so it doesn't stack with itself or other attack modifiers. In the same way, you don't get 4x slow from getting four Frostwolf skulls or -24 armor by getting 4 shieldbreakers.
EDIT : ninja'd =(