I have a question about Apple in-app purchases.
If a user purchases a non-consumable item that has already been purchased again instead of restoring it, does the same effect as the restoration occur, or does a new payment incur expenses for consumers?
The app has a restore button and a process to restore.
There are users who sometimes fail to restore, and I am thinking of guiding them to purchase again if the repurchase has the same effect as the restoration.
If a user purchases a non-consumable item that has already been purchased again
It's not possible to re-purchase a non-consumable. What will happen is that they will try to re-purchase it, and at some point quite late in the process iOS will pop up an alert saying "You've already purchased this". At that point, I think your app will get a StoreKit transaction for the purchase.
I am thinking of guiding them to purchase again
Yes, this is safe advice if they claim that "restore" doesn't work. The danger is that they have mis-remembered what they have previously purchased, or that they are using a new Apple ID. In that case, they will be charged.