Someone suggested on the previous thread that they might do a "Surprise, you're both through", like DWTS did recently. It sounds a bit too gimmicky and cruel for Strictly...but I wondered if they might do their own take on it: announce on the show that the judges will get the choice about whether to save both, but stress that they may well choose to save only one, so that's why it's still important to vote for your fave.
I still think it's probably unlikely...but it would be in keeping with why BBC are mysteriously refusing to confirm either way that there will be an elimination, saying instead that there will be an announcement on the show tonight.