How do I prevent Quicken from matching downloaded transactions to already reconciled entries?
More info needed in order to help you.
When you do TOOLS, Account List … what shows in the "Transaction Download" column next to the account(s)?
Have you recently changed the download method, say from Direct Connect to Express Web Connect(+). OR, have you "reset" the account download?
About how long has this been happening? From a single financial institution? Or many? If many, please answer the above questions for each of them.
I have been having the same problem for about a month with Wells Fargo, I have deleted the downloaded duplicate from the download, I have tried accepting and then duplicating from the reconciliation page, but they recur every day, essentially every transaction for the past month.