Can anyone help me with this inventory tutorial?

I watch some of tutorial of inventory and among them the one that not really complicated and easy to do is this youtube.com/watch ofcourse i want to try other tutorial too, but right now my focus is on this...

the problem right now is:

1. what is the solution when i have more than 1 item?

2. and i don't want to create more than 1 or duplicate it. if there is 2, i want one of them is deleted. but i don't know how to this...

anyone?

sorry for bad eng, i tried my best to deliver...

That tutorial is just for a very basic inventory where item sprites are not differentiated. What you're describing probably needs an array where the item is in one row and the amount of them is in the next row and you grab the data. That isn't a great tutorial because it doesn't really help you make a complex inventory, you'd have to start again. It only really covers the drag and drop functionality of placing items into slots, not storing different types of items, amounts of items and checking for the same item. I would look at arrays!