Need to add a /blacklist for my dupe skript

[pete_parker]

command /dupe:
	cooldown: 180 seconds
	cooldown message: &4&lHfc&3&o&lX&f&lDupe > &7 You can use this command in &d%remaining time%!
	trigger:
		if player's held item is air:
			send "&4&lHfc&3&o&lX&f&lDupe > &7NO DUPING AIR ! "
			cancel the cooldown
			stop
		if player's held item is bedrock:
			send "&4&lHfc&3&o&lX&f&lDupe > &7This item is &0&l&oblacklisted ! "
			cancel the cooldown
			stop
		if player's held item is mob spawner:
			send "&4&lHfc&3&o&lX&f&lDupe > &7This item is &0&l&oblacklisted ! "
			cancel the cooldown
			stop
		set {_item} to player's tool
		give {_item} to player
		send "&4&lHfc&3&o&lX&f&lDupe > &6&lDuplicated &e&l%player's tool%&6&l!" to player

As you see a basic dupe skript, and so far my "blacklist" is 

		if player's held item is bedrock:
			send "&4&lHfc&3&o&lX&f&lDupe > &7This item is &0&l&oblacklisted ! "
			cancel the cooldown
			stop
		if player's held item is mob spawner:
			send "&4&lHfc&3&o&lX&f&lDupe > &7This item is &0&l&oblacklisted ! "
			cancel the cooldown
			stop

wondering if i could make it where if i held an item out , i could /blacklist , which it would add it to the blacklist list , Can anyone help me with this one?

[_Tarna_]

In the blacklist command, add the player's tool to a list variable like {blacklist::*}. Then in the dupe command, check if the list variable contains the player's tool. If it doesn't, then you can dupe it. 

[S5_FrozTie]

So i Can dupe more then 1 piece of the item i blacklisted is there a way to fix this so i can dupe it at all