It's weird. I just tried reccing your reply, and the display changed from Rec (0) to a yellow-highlighted Rec'd (1), then when I clicked on it again, it returned to Rec (0), as I'd expect/hope. (This is in Skinner Mode, BTW, and it doesn't read Undo.) Unless I was having a brainstorm of some sort when I encountered the problem earlier, I've no idea what happened. I don't make a habit of trying to double-rec, but if it happens again, I'll let you know.
Probably completely unrelated, but on DU3 one time I reported a seeming bug which had allowed someone to rec an OP twice - their name appeared twice in the rec list - and that was the only time I ever saw that happen.
As for the jury service issue, yes, I was looking at the post on the thread itself. I know it may be frowned upon, but sometimes I want to have more context before I make a decision - e.g. I might cut a newcomer more or less slack than a regular in certain circumstances, but there are other situations. Now I know it's an acknowledged artifact down to my own misbehaviour, I'll just use the voting tool on the originally displayed post.