I am using a Civi install that was originally part of a Drupal installation. A month ago I switched over to using Wordpress and migrared the Civi install to Wordpress.
Since then, something weird has been happening with event registrations in CiviCRM.
Previously, under Drupal, if two people registered using the same email, it would create separate contacts for each person. Or, if someone registered using an email that was already in the database, it would do the dedupe search and either count it as the person if the first name, last name, and email matched, or else it would make a new contact if they didn't match perfectly.
Now, however, it automatically overwrites any previous entries when someone registers using an email that is already in the database. This is fine when it's clearly the same person, but for some reason, it is now overwriting even when a single part of the name is the same. So, for example, Bob Smith email@example.com registers. Then Mike Smith firstname.lastname@example.org registers. Looking at the registrations, I now have 2 registrations for Mike Smith, and there is no registration for Bob Smith. Even just the same last name has caused the first name and email to be overwritten.
I am using the same default dedupe rule, but for some reason it is acting differently now. Does anyone understand what is going on, or how I can fix this so it behaves the way it used to?