While I have my customer been charged twice?

[Aimhi]

 I made one transaction. The customer has show me his statement has duplicate charges. I only have one deposit into my account.

[RHatch]

If this was the same day or a couple days from the purchase it is probably a pre-approval charge.  These will go away as they are just a pending transaction.  If it has been some time since the transaction you will need to contact support.

[EJ_]

Hi @Aimhi

Sorry if this alarmed you. 

If you only have one transaction appearing on your Square account activity, that indicates that your customer was only charged once. 

As @RHatch mentioned, your customer is probably viewing a pending charge that will fall off of their account in a few business days. This process is controlled by your customers bank.