We don't currently have search features in OLLY, although we are looking into adding that in the future. What you may want to do for now is use categories to organize the books (and other resources) so that you can check a short list rather than a long one. To create a category, drag one resource onto another and it will group them, that category can be renamed and resources can be dragged in and out of it. Categories can also be nested for multi-level organization. So for example, you could have a Math category with either all of the books related to math in it, or if you have a lot of those, break some of them into a High School Math subcategory, or something along those lines.
Once you have a good category organization, determining if you already have a book would hopefully be just a matter of going to the correct category and looking through the list.
I hope that helps!