How can I prevent a customer from using a discount code twice?

[Vanshikaaaa]

One of my customers was able to use the discount coupon twice even though it allows one use per customer only. How did that happen? How can I avoid it?

[Michael-Thomas]

"Hello Vanshikaaaa,

I've noticed where customers might be creating additional accounts to bypass certain restrictions. You can verify this by cross-checking both orders, clicking on the customer profiles, and seeing if the same email was used.

Another possibility is the existence of duplicate discount codes, which could inadvertently trigger the second one. However, I'm unsure if this is even possible.

If neither of these scenarios applies, it might be a Shopify bug. I recommend reporting it to their support team for further investigation. They should be able to clarify if it is indeed a bug or see where things may have gone wrong. 

Best regards,"