Charmed: Demon Dopplegangers by Greg Elliot
When Paige starts her new job at the museum as a tour guide through the Greek antiquities display, she is fascinated by the ancient treasures almost as much as she is by her fellow tour guide, the gorgeous, Chase. One day, a strange stone egg is added to the collection. It gives Paige the creeps and she's sure there's something evil about it. Her fears are confirmed when Chase accidentally opens the egg and releases a demon. The demon promptly assumes Chase's form and when Paige tries to kill it, the demon Chase splits in half, forming two new wholes. With the real Chase unable to explain what happened, and doubling demons on the loose, the Charmed Ones will have to count on the Power of Three to figure out what's going on. . .