iPhoto Library Manager helps you to organise all of your photos, allowing you to browse and search across all your libraries directly from one place.
To avoid duplicate photos, iPhoto Library Manager lets you analyze your libraries side by side, giving you the opportunity to delete any extra copies that you don't really need. The application also enables you to merge multiple libraries into one, whilst removing duplicate photos in the process.
A great feature of this application is that you can create multiple iPhoto libraries rather than storing everything in one mammoth library. Having a larger number of smaller libraries means you can archive photos that you don't use and organise the ones you use more often into categories, gaining you quicker access to the files you need, when you need them.