Consider the following comment thread.
This will not work, the foos are all wrong --john doe @john Yeah, the bars too --john smith
If I reply using
@john it will notify "john smith" but not "john doe". How do I reply to "john doe"?
How do I reply to someone named "BA Baracus"? Will @BABaracus work?
What if the name is "B. A. Baracus"?
What if, in the same comment thread, someone else is named "BABaracus"?
Note: I have read Meta Stack Overflow question How do comment @replies work? and Display names with spaces in the first few characters cannot be used in @ responses.