How can I verify whether students completed their Illustrator assignments themselves or modified the provided End files?

Hi, I’m a Teaching Assistant for a graphic design course. My instructor and I have been having issues with students submitting the completed End files from Adobe Classroom in a Book lessons as their own work. Some even modify the End files before submitting them.

We now require students to submit their original Illustrator and Photoshop working files (.ai). Is there a reliable way to check a file’s editing history or determine whether a student worked through the lesson themselves instead of modifying the provided End file?