As a mismatch uploader I want to understand why some of my mismatches are not imported.

Problem:
We are going to ignore uploads of duplicate mismatches that have already been reviewed before in T329631. We need to make sure uploaders are not confused about some of their uploaded mismatches not making it into the mismatch store.

We probably want to add clarifications about this to documentation or to the upload overview page.

Screenshots/mockups:

BDD
GIVEN
AND
WHEN
AND
THEN
AND

Acceptance criteria:

Open questions: