How would you make the basic ROBLOX drooling zombie not kill other zombies?

I'm trying to make a zombie - type game, and when I test it, it goes well, but the Zombies keep killing each other when they're in a certain radius. Here's the script, and what should I do to prevent this issue?

local zombie = script.Parent

for _, script in pairs(zombie.ModuleScripts:GetChildren()) do
    if not game.ServerStorage:FindFirstChild(script.Name) then
        script:Clone().Parent = game.ServerStorage
    end
end

local AI = require(game.ServerStorage.ROBLOX_ZombieAI).new(zombie)
local DestroyService = require(game.ServerStorage.ROBLOX_DestroyService)


local function clearParts(parent)
    for _, part in pairs(parent:GetChildren()) do
        clearParts(part)
    end
    local delay
    if parent:IsA("Part") then
        delay = math.random(5,10)
    else
        delay = 11
    end
    DestroyService:AddItem(parent, delay)
end

zombie.Humanoid.Died:connect(function()
    AI.Stop()
    math.randomseed(tick())
    clearParts(zombie)
    script.Disabled = true
end)

local lastMoan = os.time()
math.randomseed(os.time())
while true do
    local animationTrack = zombie.Humanoid:LoadAnimation(zombie.Animations.Arms)
    animationTrack:Play()
--  local now = os.time()
--  if now - lastMoan > 5 then  
--      if math.random() > .3 then
--          zombie.Moan:Play()
----            print("playing moan")
--          lastMoan = now
--      end
--  end
    wait(2)
end