Importance of Being Earnest- English

I'm an English teacher and we are currently working with a satire unit, reading the playThe Importance of being Earnest, some of my kids went out and bought the book, and they have a version with 4 acts. There are new characters, new situations, it's completely different. Has anyone else encountered this? Does anyone know if the 4 act version is just as good? Where did this 4 act version come from? Nobody in my department had ever seen a version of this play with 4 acts. Any insight you can add would be greatly appreciated.