Card that can clone into player's backpack if unowned (Intermediate)?

This is my code:

--//Service
local ReplicatedStorage = game:GetService('ReplicatedStorage')
local Players = game:GetService('Players')

--//Variables
local Player = Players.LocalPlayer
local Keycards = ReplicatedStorage.Keycards:GetChildren()

--//MainScript
script.Parent.MouseButton1Down:Connect(function()
	if Player.Backpack:FindFirstChild('Keycard') == nil then
		if Player.Character:FindFirstChild('Keycard') == nil then
		
		local GetKeycard = Keycards[math.random(1, #Keycards)]
		GetKeycard.Parent = Player.Backpack
end
end
end)

The problem with this code is that another person who clicks the GUI will get the card even if it is owned. I would only like the card available to one person in the whole server, basically just one different card per person.

Any help please?

Try using a for loop to go through all players to see if they have the card. Hopefully this is what you were looking for. To better understand how these work here's the wiki article on them.

script.Parent.MouseButton1Click:connect(function()
	local availableCard == true
	for i,v in pairs(Players:GetChildren()) do --"v" would represent each player 
		if v.BackPack:FindFirstChild('Keycard') then 
			availableCard == false
		end
	end

	if availableCard == true then
		local GetKeycard = Keycards[math.random(1, #Keycards)]
        	GetKeycard.Parent = Player.Backpack
	else 
		print("No card for you! >:O")
	end
end)

I found out! Thanks for helping.