This is one of these stories where the protagonist has to deal with her magical double. This was originally printed in 1983, then in 1997 it was reprinted with a name change. I think the second title suits the story better. Margie’s Magic Book implies Margie doing spells when in reality she uses it once, then her other self hides it so she spends most of the story looking for it to reverse the spell. So I wouldn’t really call it her book. “That Girl’s Me!” seems to sum up what the story’s about more accurately.
The protagonist, Margie is a nice girl, though not the most outspoken or highest of school achievers. For a school project about local superstitions and legends, she researches a legend of Old Mother Wily a witch and goes to the ruins of her cottage. There she finds the magic book which releases her other self.
Her double describes herself as the Hyde to her Jekyll, the part of her that dares to do what Margie won’t. Of course the whole Dr. Jekyll and Mr. Hyde story didn’t end too well for the Jekyll. These Jekyll and Hyde type stories that were common in these comics, and often did not end well for the good protagonist. In one Judy story “The Image of Iris” Iris’s double Siri ends up trapping Iris and taking her place permanently.
But Back to Margie and her double. Her double starts taking Margie’s place and making trouble. Usually Margie showing up just in time to receive the trouble. The Double excels at table tennis and annoys the previous champion and insults her as well. The Double also excels in schoolwork but she also insults teachers. When Margie turns up at school it’s her that has to face the gang of girls that the Double has annoyed but her double helps out with a bit of magic, and sets a dog on them.
Margie knowing that her double is using the magic book to learn spells, follows her double to find where she has hidden it. Later while her double takes her place in a race, Margie takes the book and hides it in a new place.
Later she goes back for it but her double appears, she asks Margie to trust her and she’ll fix everything.
Honestly she doesn’t look trustworthy, she looks more creepy and evil but Margie figures she can’t defeat her so she gives in. The Double does a spell from the book and she disappears. Margie feels happier and more confident. Turns out they have merged. She finds herself excelling in running and table tennis, though her academics slip a bit which she figures is her old self slipping out. Overall she’s happy herself and her double make a good team.
So things work out for Margie, but throughout the story there is a bit of suspense on how things will work out. At times the double does try to help Margie, but at the same time the artwork can depict the Double in much more creepy and evil light, that we can’t be sure of her motivations.