Need help solving item duplication – Modding Tutorials

I did some research and wrote some code in order to prevent item duplication.
What i am trying to do is very simple actually. When a player is already doing staff in the inventory, disable access to it.

What i did so far:
My problem is that when i hit E to open the inventory i get the message it turns to true and returns to me and i receive the notification also other players can access the inventory!

Client Event

RegisterNetEvent('popOpenTheMenu')
AddEventHandler('popOpenTheMenu', function(canOpen)

	
	if canOpen == false then
		OpenArmoryMenu(CurrentActionData.station)
		print(canOpen)
		canOpen = true
		TriggerServerEvent('esx_policejob:menuopen', canOpen)
	else
		print(canOpen)
		ESX.ShowNotification('This inventory is not accessible right now!')
	end

end)

Server Event

canOpen = nil

RegisterNetEvent('esx_policejob:menuopen')
AddEventHandler('esx_policejob:menuopen', function(canOpen)
	if canOpen == nil then
		canOpen = false
	end

	if canOpen == false then
		TriggerClientEvent('popOpenTheMenu', source, canOpen)
		print(canOpen)
			
	else
		canOpen = true
		print(canOpen)
		TriggerClientEvent('popOpenTheMenu', source, canOpen)
	end


end)

Thanks for your time!