No. It's not a bug, maurociaccio.
If the payments are from the Banking page, there's no need to enter a Sales Receipt. Instead, we'll have to match it to the existing transaction. In this case, we'll have to undo the duplicate transactions. I'll show you how:
- From the Banking menu, select Banking.
- Go to the Reviewed tab.
- Tick the duplicate transactions
- Click the Undo button.
- Go to For Review.
- Select the transactions, and then select Exclude Selected from the Batch actions drop-down.
Since you've manually entered the payments, we'll need to delete them. Here's how:
- From the Accounting menu, select Chart of Accounts.
- Locate the account and click Account history.
- Select the transaction and select Delete.
I've added this article to know more about the Sales Receipt transaction: Should I use an invoice or a sales receipt?
I'm just around if you still have other concerns with your transactions.