Hello,

the User Notifications are a bit off it seems. Basically there are two issue: 

1.) Once a user who I've subscribed to makes a comment, I get notified twice.

2.) Whenever a user mentions me with  @ , no notification is fired although the setting for this is activated. Also one should know that the User & Comment Mentioning Addon is also installed. 

Please have a look at the screenshots. Yes, I tried both Ajax & REST.