I found the solution which worked for me. This Adobe help article explains the steps, which are as follows (added in case the link goes down):
After backing up your catalog, relaunch Lightroom.
Connect the hard drive (MyBook) that is repeating twice.
In this article, the labels—MyBook, Temp, Fred, and Mary—have been used as representative names to ...
Adobe Bridge is free and very easy to use. It includes a keywording tool, a starred rating system and colour-coded labelling which can all be helpful when searching for particular images in your library.
Adobe Lightroom is a good photo library software, in addition to being a powerful post processing tool. It is however not legally free.
I used Picasa in the past, which I liked a lot, I think it has been discontinued, but it must be possible to find older versions that are working.