After a couple of tries this allows me to use the same code multiple times?

local Data = game:GetService("DataStoreService"):GetDataStore("Codes")

local On = game.ReplicatedStorage.Remotes.Codes

function Reward(plr,code)
	local SavedStuff = Data:GetAsync(plr.userId)
	if SavedStuff ~= nil then
		for i,v in pairs(SavedStuff)do
			if v == code then
				return "Already Redeemed!"
			else
				if game.ServerStorage.Codes:FindFirstChild(code) ~= nil then
					local RealCode = game.ServerStorage.Codes:FindFirstChild(code)
					if RealCode.Value == "RewardPoints" then
						local Points = plr.leaderstats.EmPoints
						local SaveCode = {}
						table.insert(SaveCode,code)
						Data:SetAsync(plr.userId,SaveCode)
						Points.Value = Points.Value + 150
						return "Redeemed!"
					end
				else
					return "Invalid or Expired Code!"
				end
			end
		end
	else
		if game.ServerStorage.Codes:FindFirstChild(code) ~= nil then
			local RealCode = game.ServerStorage.Codes:FindFirstChild(code)
			if RealCode.Value == "RewardPoints" then
			local Points = plr.leaderstats.EmPoints
			local SaveCode = {}
			table.insert(SaveCode,code)
			Data:SetAsync(plr.userId,SaveCode)
			Points.Value = Points.Value + 150
			return "Redeemed!"
		end
		else
			return "Invalid or Expired Code!"
		end
	end
end

On.OnServerInvoke = Reward

For whatever reason, this script is supposed to save the code that the player used and when I use the code after like 2 seconds it allows me to use it once again, I have no clue what is happening here.