Review your transactions.
You should only have one Stock Split transaction recorded (in any one of your investment account registers ... that transaction applies to all holdings in all registers)
If the brokerage downloaded Add Shares transactions, delete them. That's what most likely causes your duplicates.Also look for Placeholder transactions and get rid of them.
If you sold a Mutual Fund ... where's the Sell transaction in your register?
Thanks for the reply but it seems there is a mis-understanding, as I've said, there is NO way to delete them! That is the issue. The investment house count is correct, Quicken is wrong. There should be a way in Quicken to edit the # of shares and also to delete transactions so your investment accounts can reconcile with your investment house. If not, then Quicken has a system that is not accurate and financial books that are not trusted, are not useful. Should be a simple software editting fix. If anyone knows how make the edit, please reply.