• No, that happens relatively rarely. For comments on the site, you two must both have commented on a post (or one of you have written or edited the post) for that to occur. Otherwise, the software knows which of you is meant by @111. In chat, it happens if both of you were active in the room in question not too long ago. Then the software doesn't know whom @111 refers to, and pings you both, iirc. – Daniel Fischer Jan 12 '17 at 16:06