I have not seen this before, but a badge I earned a long time ago appeared in the recommended badges. Not sure if that is supposed to happen, or if it still thought I was on an alt when it suggested them?
Seems like it might be the same kind of issue that causes the recommended games module to occasionally recommend me games that I’ve rated before. Personally, I haven’t seen it happen with the badges yet, though. Have you tried clearing your cache to see if that makes it re-recommend the badges or changes anything?
I think the problem might be you having so few unearned badges, so that they don’t fill up the recommended badges list and it has to add badges you already have.
It’s weird that it went back to normal a few hours later though, that was the first and only time it has been like that.
Also, when it was like that, the second page of recommended badges was filled with 6 that I didn’t have, which makes it even stranger that it only showed 5 on the first page.