QuickBooks uses both amount and transaction dates when looking for a match instead of transaction numbers. It's considered a Match if they have the same amount and the transaction date is within 90 days.
You'll see multiple possible matches if there are several transactions with the same amounts that are within 90 days. To give you more details on how QuickBooks handles banking transactions, please see this article: Add And Match Downloaded Banking Transactions.
I'm taking notes of your suggestion about using transaction numbers when matching banking transactions and will forward this to our engineers. Customer suggestions are always used whenever updates are designed to improve our products and services.