Should quickbooks create a duplicate transaction, e.g. accounts receivable (payment) and deposit (sales) for the same customer can it just be deleted?

Thanks for posting here. @Equilibrium.

Let me share insights about transaction duplicates and what we can do to remove this.

QuickBooks shouldn't create duplicate transactions, especially for the same customers. Moreover, deleting these duplicates is generally safe. However, there are a couple of things to consider before doing so, such as identifying the source of the duplicates. 

If it's a manual entry, we can directly delete them. Here's how:

1. Go to Sales, then Customers.
2. Look for the Customer that has the duplicated transactions.
3. In the Transaction List. You can filter it to specify the transaction in the Type, Status, and Date fields.
4.  Click the duplicate transaction. If it's an invoice, ensure to delete the payment made by clicking the Clear Payment tab below the transactions to zero it out.
5. Look for that transaction again. Then, click the dropdown icon beside the Edit/Receive payment.
6. Choose Delete.

If the duplicate is from the bank feeds, undo the added entries. Then, match them to existing ones to link them and avoid duplicates. Feel free to follow the steps below:

1. From the Transactions tab, choose Bank transactions.
2. Go to Categorized.
3. Look for the duplicated transactions, then click Undo below the Action column.
4. Go back to For review, click the transaction we undo.
5. Pick Find match.
6. If multiple match shows, check if it's correct. Once done, click Match to remove duplicates.

Furthermore, you can also run the Transaction list by Customer to look for the duplicated transactions. Feel free to read this article for more info: Find duplicate transaction numbers in QuickBooks Online.

You might want to automatically categorise transactions from your bank. You can read this article: Set up bank rules to categorise online banking transactions in QuickBooks Online.

Never hesitate to come back here if you have additional questions about managing your customer transactions. I'll be willing to lend a hand. Have a good one.