So we have a few options here
a) They're both cannibals and working together
b) They're both cannibals but have no relation to each other
c) Only Handa is a cannibal, Helmet is trying to protect the group from Handa
d) Only Handa is a cannibal, Helmet is an evolved carrier
e) Only Handa is a cannibal, Helmet is a third party murderer, though not necessarily a cannibal
f) They're both cannibals, but Helmet has been trying to protect them while holding back his urges, whereas Hanada has been going around eating people (not likely - Handa himself mentions that he wants to try eating humans for the first time)
I'm probably overlooking something, but that's all I can think of atm ...