If I get you correctly, you are experiencing this error when using the DocumentManager of the content block, is that right? Can you please let me know which build version of Sitefinity you're using, as in the latest versions we're displaying a list of the uploaded documents, not a thumbnail view, and this problem does not reproduce there. The screenshot I've attached to this reply is made with our latest 4.1 SP1 version. I believe it was build version 1210 (SP1), where we introduced a change - before we used to display the documents in thumbnail mode, and this indeed caused overlapping of document's names, so we switched to list view to avoid this problem.
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