First it is important to recognize the two download sources for prices: a) the brokerages (Fidelity and Vanguard) and b) Quicken's servers. You can determine which which source is feeding bad data by selectively downloading rather than all inclusively downloading. When (if) using a One Step Update, click the settings button after when entering your Pin vault password. You can also use the straight Download Quotes selection to get only the Quicken server data. The brokerage data always matches their security information to your Quicken security through a CUSIP number. The Quicken server data always matches based on the ticker. From your description that the two have different tickers, it would seem that there is a mismatch in the CUSIP connection. To correct that matching, Edit both security details and uncheck the box for "Matched to Online security". When you next initiate a download from the brokerages, you will get the option to re-match both securities to the two Quicken securities. That should clear the issue.
The Match Securities dialog appears only if you've downloaded a security that Quicken is unable to match to one of your existing Quicken securities. (Quicken automatically matches a downloaded security if it has the exact same name or ticker symbol as one of your Quicken securities.)
I would be inclined to look in the OFX log and see what the CUSIP the financial institutions are sending for both (Help -> Log Files... -> OFX Log)Here is a typical entry:<SECID><UNIQUEID>494368103<UNIQUEIDTYPE>CUSIP</SECID>It might tell you if somehow (should never happen) they are using the same CUSIP.
Running Quicken 2014. Been a Quicken user for at least 20 years - started on a MAC SE. Have problems over time but usually able to figure it out. I've been fooling around wit this issue off and on for a year or two. No CUSIP number shows on Edit Security Details. The tickers are different - in Vanguard portfolio - VAIPX. In Fidelity portfolio - VIPSX. Don't understand you last para ...