You don't need to know that Baby Peggy had a $1.5 million contract in the 1920s to know that between Jackie Coogan and Shirley Temple she was the biggest smallest thing in Hollywood. You'll know that if all you've seen of her is "Miles of Smiles," because you have to be a big deal to headline a studio picture by playing dual roles--Mary Pickford, Douglas Fairbanks, Charlie Chaplin, even Eddie Murphy or Nicholas Cage--and not have some no name on the internet calling what you did, Seth Rogen, a vanity exercise....
Anyways, so here child star Baby Peggy plays twins, which was presumably accomplished with the usual tricks of the day in substitution-splices and double-exposure cinematography. Interestingly, the film begins with a shot of apparent real twin babies before some time passes and the two Baby Peggys are separated for much of the proceedings, as one of the twins roams off and is adopted by a guy around the block running a novelty train business, or rather makes Peggy run it for him. It would seem that years have passed if the same characters are replaced by other actresses, which raises the question, given how close by this lost daughter appears to have lived in that time, did the parents even look for her or report her missing?
One twin raised by neglectful parents and another raised by a show-business employer who, in the end, abandons her for a payoff. It's sad how much this plot resembles Peggy's reported real-life situation as a child star. Again, see the informative documentary "Baby Peggy, the Elephant in the Room" (2012) for more on that.
Otherwise, the resulting twin mix-up escapades are amusing enough. I especially like the train business, though. I've already talked about how cinema and trains reflect each other as forms of modernity that change the way we see the world, just as I've ruminated elsewhere about twins reflecting the reproducible quality of motion pictures, but there are other reasons to appreciate such mirroring here. During the running around in the family's house, the adoptive father's gang and the girls crawl about, visually resembling the train and its box cars from earlier. There's also a good gag regarding the lost twin being found on that tiny train's railroad track--referencing a melodramatic cliché of damsels in distress, although apparently not necessarily a silent-film one as sometimes misbelieved, which isn't to say a few films haven't gone there, but they tend to be parodic, as here.