CRM 4.0 Duplicate detection

There are a few oddities with the duplicate detection and how delays in when it updates its internal list of “duplicates to check” by running the MatchCode system jobs can cause unpredictable results.

• If you enter a phone number for a contact and then enter the same phone number immediately afterwards for a different contact CRM may not have run its "matchcode" job yet to update its internal duplicates list that runs every 5 minutes and not detect the duplicate. Entering the phone number, waiting > 5 minutes and then trying the same phone number for a different client should allow CRM to "catch up" and detect the duplicate
• Duplicate detection popup appears but list the “potential duplicates” in the bottom section of the popup as “None”. This happens occasionally when a record is flagged for deletion but the Async windows service has not cleared it down yet. This is a timing issue that should not happen regularly....

This mostly showed up when our customer was testing and Contacts and Accounts were being added/updated/deleted in quick succession.