Every so often here on the Upper West Side, yet another Mommy and Me type hurries across the street with a double-wide stroller, and neither of its seats is occupied by the usual fare. I want to ask if she knows that, in her mad dash across Broadway, her dual babies bounced free in tandem, dumped onto the sidewalk, and are no doubt flailing on their backs (babies land on their backs as surely as cats land on their feet). But I am quite sure they would look at me as if I had actually dumped the babies out myself.