I've seen a number of questions on this site suggesting that there may be problems with the deduplication rules, e.g.: Why am I getting duplicate contacts for contributions?
My individual unsupervised rule checks against first name, last name and email address. No length is set for any field, all have a weight of 10, and I've set the threshold at 25. When I run this rule as an administrator it successfully finds the duplicate records, although the results list present the 'Threshold' as '30' when I display that column, which seems rather odd (maybe it is reporting the score rather than the threshold?).
But when users are registering for events through the standard registration form, duplicate contacts are consistently being created.
How can I ensure that my unsupervised dedupe rule works as I expect it to?
Running CiviCRM 5.13.5 on Drupal 7