As you watch "Twice Blessed", it's obvious that this film was later remade as "The Parent Trap" by Disney. However, if you check the IMDB pages for each film, they claim to be written by different writers...which is odd since the Disney film clearly wasn't just inspired by "Twice Blessed"...it is, essentially, the same film with one major difference. Instead of using one actress to play both twin sisters, in this original actual twins, Lyn and Lee Wilde, play twin sisters.
Jeff and Mary (Preston Foster and Gail Patrick) are godawful parents. After they divorced, they separated their twins...with Jeff taking one and Mary taking the other! While the girls get to spend a little time together, they essentially live separate lives because the parents are jerks. On a lark, the girls agree to switch places without telling their parents...and both have difficulty adjusting to their sister's very different lives. Goofiness ensues. At the same time, their parents start reassessing their divorce.
While you'd THINK both sisters would be very similar because they are identical, oddly in this film they are totally different...with one being a swing-loving teen and the other being a super brainiac. Oddly, the brainiac needs glasses...the other doesn't! To me, this is a weakness of the plot and makes the switch seem a bit silly. Another weakness is the unlikability of the parents and the father's very nasty girlfriend, Alice. Overall, an interesting plot due to its obvious connection to the Disney films but one that really makes little sense when you think about it...something you could also say about the Disney ones as well.