Only add 1 item into backpack?

This script is used to add an item to a players backpack once they are on a certain team but when ever I test it it always adds 4 items instead of only 1.

local Tools = {
    ["Assassins"] = game.ServerStorage.Tag,
}
 while true do
	wait(5)
	game.Players.PlayerAdded:connect(function(plr)
	plr.CharacterAdded:connect(function(char)
		plr.Changed:connect(function()
            if plr.Team == game.Teams.Assassins then 
               Tools.Assassins:Clone().Parent = plr:WaitForChild("Backpack")
            end
        end)
    end)
	end)
 end	

Ok so I removed the while loop and I tried to add a check but it still adds 2 items to the players that join the team

local Tools = {
    ["Assassins"] = game.ServerStorage.Tag,
}
	wait(5)
	game.Players.PlayerAdded:connect(function(plr)
	plr.CharacterAdded:connect(function(char)
	local NumItems = plr.Backpack:GetChildren()
		plr.Changed:connect(function()
			if NumItems == 1 then
			return
			end
            if plr.Team == game.Teams.Assassins and #NumItems == 0 then 
               Tools.Assassins:Clone().Parent = plr:WaitForChild("Backpack")
			   print(#NumItems)
            end
        end)
    end)
	end)