Marcin Borkowski (mbork) posted a potentially helpful tip on multiple help buffers. I say “potentially helpful” because his use case is pretty niche and it’s hard to think of others that are essentially different. Regardless, If you need multiple help buffers, mbork shows you how.
His particular need was to compare the doc strings of two functions. If I had that need, I would probably have followed the help buffer to the source of the first function and then brought up the help for the second function. The source of the first function contains the doc string, of course, so I could compare them with a single help buffer. Mbork’s solution is arguably simpler. Take a look at his post to see how he did it.
I often comment on Borkowski’s posts but I don’t mention all of them. If you’re interested in honing your Emacs skills, his blog is a good one to follow. It’s low volume—a post every week or two—so you won’t be overwhelmed. If, like me, you have an RSS feed, you should consider adding his blog to it.