You are managing your project templates and notice that some or all of them appear multiple times under File > Setup > Project Templates, as can be seen in the screenshot below:



Even if you delete the duplicated templates, these may reappear after restarting Trados Studio.
 

To solve the problem, recreate the corrupted projects.xml file:

1. Make sure Trados Studio is closed
2. Go to the folder: C:\%UserName%\Documents\Studio 20XX\Projects
3. Find the file projects.xml and rename it, for example as old_projects.xml
4. Restart Trados Studio

The list of project templates is stored in the projects.xml file. If this file becomes corrupted, templates may be multiplied under File > Setup > Project Templates.