Trying to make 2 npcs not collide, but humanoid messes it up?

So I got this code im trying to make that should stop 2 npcsh from colliding, any help? The npcs names are HatDummy3 and HatDummy2

local PhysicsService = game:GetService("PhysicsService")
npcGroup = "npcGroup"
PhysicsService:CreateCollisionGroup(npcGroup)
PhysicsService:CollisionGroupSetCollidable(npcGroup, npcGroup, false)

local function setCollisionGroupRecursive(object) --
    if object:IsA("BasePart") then
        PhysicsService:SetPartCollisionGroup(object, npcGroup) 
    end
    for _, child in ipairs(object:GetChildren()) do
        setCollisionGroupRecursive(child) 
    end
end

npc = workspace.NPC
setCollisionGroupRecursive(npc)