When I double-click a lowercase word like “counter” on OSX (ST3) it semi-highlights all matching lowercase words.

However, when I start selected these highlighted words, it starts to also select mixed/uppercase words like Counter.

That’s just wrong.

Would like to know this as well – is there a case-sensitive alternative to Cmd-D?

Oh well, seems like the selection with Cmd-d follows the case-sensitivity setting in the search pane. The semi-highlighting should obviously do the same.