Mine lay unfertilized eggs quite a bit along with slugs and fertilized eggs. The unfertilized eggs usually start to look bad in about 12-14 days. When laid they will look like a normal egg but no embryo inside. Lizards and geckos do it as well. Way more common than laying an egg with a clone inside. Super possible to lay eggs from retain sperm. Let us know what is inside the eggs when you cut them open. I am going to guess no embryo.