The tag is present in Lintian version 2.109.24. That is the most recent version we know about.
The specified paragraph in the machine readable copyright file references all possible files but is not the first paragraph. For example:
Files: filea Copyright: 2009, ...
Files: * Copyright: 2010, ...
As the paragraphs is matched on a "last match wins" principle, all proceeding paragraphs are overridden.
Please refer to https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/ for details.