Somehow my customers invoice was paid twice with bank transfer. How do I fix this?

Thanks for sharing your query regarding the customer's overpayment, lawncare.

I've got the information on how to resolve when a customer overpays you.

QuickBooks Online offers options to handle overpayment from customers. These include the following:

• apply the credit to an existing invoice or a future invoice.
• refund the customer
• or record the overpayment as a tip.

Apply the credit to an invoice you already created.

1. Go to + New and select Receive payment.
2. Choose the customer, then the credit and the invoice.
3. Select another pending invoice and enter the overpayment amount in its Payment column.
4. Click Save and close.

Apply the credit to a new invoice

1. Go back to + New and select Invoice.
2. Create the invoice.
3. Select + New and then select Receive payment.
4. Pick the credit and then Save and close.

I'm adding a detailed resource about working with credits/overpayments: Handle a customer credit or overpayment.

Moreover, check out the following resources that contain information about categorizing transactions and reconciling your account for future use:

• Categorize and match online bank transactions in QuickBooks Online
• Reconcile an account in QuickBooks Online

You can post again of you need further assistance managing overpayments or other concerns. I'll be sure to lend a hand.