All reports of description-synopsis-is-duplicated for the archive. The extended description of this tag is:

The first line of the extended Description: should not repeat the synopsis exactly. This indicates that either the synopsis is badly formed or that the extended description has been wrongly copied and pasted.

Refer to Debian Policy Manual section 3.4.2 (The extended description) for details.

Severity: important, Certainty: certain

Check: description, Type: binary, udeb

This tag has not been emitted in any package tested by Lintian.