Easy Profile - Joomla Extension

Hi,
unfortunately Easy Profile is not compatible with this plugin.

This tells me that Easy Profile does not use the same check as com_users on the front end.

Easy Profile extends Joomla user management (not replace it), so the check is the same of Joomla.
Both Easy Profile and "Allow Duplicate Emails" manipulate the Joomla form, but Easy Profile do this in the Joomla event called "onContentPrepareForm" instead "Allow Duplicate Emails" in the Joomla event "onAfterInitialise".
"onContentPrepareForm" is a event dedicated to manipulate Joomla Forms (not only user registration)
The event "onContentPrepareForm" is called after event "onAfterInitialise", so the last plugin triggered is Easy Profile.
Among the 2 the one that best uses Joomla events is definitely Easy Profile.

Why "Allow Duplicate Emails" uses "onAfterInitialise" event? Because this plugin need to use this event to keep compatibility with older Joomla versions.

I cannot find the code Easy Profile uses when I do a search for it.

I don't know if this modification will works but you can try to remove following code to file /administrator/components/com_jsn/helpers/fields/usermail.php at line 48:

unique="true"

In Joomla version 3.8 and above, Allow Duplicate Emails literally replaces the core file /libraries/src/Table/User.php, which is what com_users uses to check for duplicate emails, with a version that has the check commented out, so the timing of the check has nothing to do with it. Easy Profile is not using the same check as com_users on the front end.

taking out the unique="true" worked.