Apologies for delay in my reply. Our developers cannot track when the recipes were added to your Bookshelves as we do not log dates of additions to Bookshelves - books or recipes. It is possible we could add that feature. Though I'm not sure how much it would help you to know when the recipe was added, since you are sure you did not add them. In our system, the only way an individual recipe can be added to a Bookshelf is by the signed-in member clicking the blue +Bookshelf button or by importing a recipe using the Bookmarklet. Recipes cannot just be imported to a Bookshelf. This isn't an issue that anyone else has reported is happening to them. But please do let us know if you feel it is still happening and we can investigate further.