Avoiding duplications

I am not sure how I managed this but I have excelled myself recently with duplicates. Which started me wondering how people manage their book lists and avoid duplicates. I even have three books especially to make lists and they remain unused.

I have started to take photo's of all of mine and I am going to add them to my bookshelf page on this website. I have looked into online solutions available. I do have a Good Reads account but that is reasonably new and I want to add my own pictures not the covers on there, as they are not always reflective of the edition I have.

1. Goodreads - is a social cataloging website you can add all your own books and create a database of books, annotations, quotes, and reviews. You can also create your own groups inviting your friends and making new ones. Where you can discuss book suggestions, recommendations, blogs, and polls etc. Goodreads is owned by the online retailer Amazon.
   

2. Libib - Is an online home library management app. it can be used books, films, music, and video games.
   

3. Delicious Library - Now in it's 3rd release, it is software where you can categorise your books, music, films and video games.
   

4. Library Thing - This is another social cataloging website for you to add your books. You can share what you are reading, what you want to read, reviews and recommendations.

5. Book Crawler - A personal library on an app. An app that is only available on Apple products

6. Collectorz - An online cataloging site for your books, films, music, comics and games. It works on your phone, tablet or computer and sync data between them.

Like I say I have a Good Reads account, which I really must use more and have not tried and I am not recommending the others. I just wanted to bring some of the tools available to you, to avoid duplications.

What do you use?