It's possible that one of the Chase credit cards was set up as a sub-account and the other as a parent account in QBO. If the parent account is connected to the Banking page, the transactions from both accounts will be downloaded to the parent one. If the sub-accounts are connected, the transactions will be downloaded to the individual accounts.
To check if the credit card is a sub-account or a parent, please follow the steps below:
Open your QuickBooks Online (QBO) account.
Go to the Accounting menu and choose Chart of Accounts.
Find your chase credit cards and click the drop-down arrow under the ACTION column.
Pick Edit and then see if the Is sub-account box is checked. It indicates that an account is under the parent account.
If both credit cards are not set as sub-accounts, I recommend contacting your bank to further check how they send the downloaded transactions.
To give you more details about this procedure and help review your accounts to ensure they match your real-life credit card statements, please visit the following: