You've probably been downloading titles with the wrong aspect ratio for your current project. For example, the tiles have an aspect ratio of 4:3, but your project is set to 16:9 or 9:16.
Try changing the project's AR setting to match what you've downloaded:
You should now see all of the unwanted installed titles in the Title Room, and you can right-click on each one to delete all but one of them.
Next, set the project AR to the correct value for your current project and go back to the DZ website. You'll now want to set the results filter to the matching AR. This time, every available item will show up after downloading and installing.
You may also want to read this
post, which describes the process along with tips for not losing your place in the search results.
YouTube/optodata
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