I have witnessed at least 10 splits, never seen 2 mouths. They split at the mouth, rips it in half. It needs a week or 2 to heal and regrow mouth afterwards. I usually can tell by the foot spreading and elongating to rip itself in two.
Yours looks like one of mine after a split where it closed up and still needs to fill in and regrow tentacles. It could just be a little deflated in that one spot, but they can fool you, you may wake up tomorrow and have 2. Sometimes you just can't tell.