Original illustrations by DyAnne DiSalvo, though my copy is
a re-release with illustrations redone by Carol Thompson.
I have this story in Two Times the Fun, a collection of the Janet and Jimmy stories. It seems like an Easy Reader story on its own, but Google shows they were kind of a picture book/Easy Reader hybrid. I like them as a collection because I think they work well as a beginner chapter book. The twins are only four, though, so I can see the reasoning behind making it a picture book parents would read to their four-year-olds.
Janet loves to play pretend, but Jimmy loves things that are real. When he digs a real hole, Janet wants to pretend it's a nest or a fishing pond. Jimmy doesn't like that, but he doesn't know what he could use the hole for.
This book is pretty simple but it's fun and light-hearted, and I think kids would love it because it's definitely how kids act.