Stock Splits

"As far as I can tell Fidelity sends out one notice of a stock split which Quicken handles well. Then a day later Quicken does an add stock as well, doubling the number of shares. "

I can't follow along with your explanation.  You appear to be saying that Fidelity downloads the stock split information to Quicken but, as far as I know, Fidelity can't kick off Quicken' "Stock Split" action on its own, so I assume (correct me if I'm wrong) that they send you some number of Add actions instead.  If that's the case then the correct approach here - one that gets all you lots properly stated - really is to delete those Adds and enter a Stock Split transaction as of the appropriate date.  Getting this all properly stated typically requires that you change the downloaded stock quotes for a few days before the split actually takes place as Quicken's stock quote provider typically sends "split adjusted" quotes to Quicken before the actual split date.

Your second sentence doesn't make sense to me since Quicken, on its own, typically never "makes entries" out of whole cloth.  Any entries it does make have to be, somehow, either set up by you (e.g., Reminders") or made in response to your approval, (e.g., it notices that the number of shares don't agree to what the broker says is the correct number, and asks if you want a placeholder entered, to which you agree.)  Is this second set of entries actually Placeholders?  It does seem like Quicken can get confused with splits and propose Placeholders when they are not actually needed.

I'd say the best approach to splits and the one that will result in the most accuracy is to not accept downloads for splits but instead use the Stock Split action as of the correct date, fixing the split-adjusted quotes for the previous few days.  If Quicken thinks that the stock split hasn't been entered and suggests a Placeholder, you refuse.