How can I make layout items to not be created again

I'm trying to make a sidescrolling platformer and one of the last addiction was the layout switching, back and fourth.

The problem I'm encountering is, if I place enemies, items and so on and go forward, whenever I go back to the layout again, the enemies and items are created again.

How can I tackle this?

Give them the Persist behaviour or make them global objects.

Give them the Persist behaviour or make them global objects.

If I do that they will stay for sure, dont they? I want you to be able to grab the coins only once and if you go back, the coins are already "grabbed"

You could initially create the coins based on a global variable being 0 and if they are collected set it to 1, so when you return they won't be created.

You could initially create the coins based on a global variable being 0 and if they are collected set it to 1, so when you return they won't be created.

Is this the most effective way to make a sidescrolling game objects?