I tested it today on that URL using a couple of different browsers – mobile and desktop- but I could not duplicate the error and on checking, not all two-part names gave this error. The user who let me know about it, uses a mobile browser.
I cleaned things up and deleted all the extra “+” characters and found they went back to July 22. So the issue started then.
Just now I got in a new comment on that same post and again the extra character appears in the name: “Mark+Berger” Normally he does not use the +.