A bank feed imports movements from the bank. It does not know whether those movements are already in your books. Review each line before acting. Add creates a new transaction with a category. Match links the downloaded line to an existing transaction. Exclude keeps a duplicate or non-book item out of the accounting records.
An existing invoice payment or bank deposit should normally be matched, not added again as revenue. A transfer between your own accounts is also different from income or expense. Check the amount, date, payee and bank account. A matching amount alone is not enough when several transactions share the same value. The categorized tab should retain the link so a mistaken choice can be undone.