"More than one file is matched to the same post"

Quick answer

Two or more staged files are proposed for the same destination, so running them would make each overwrite the last — and only the final one would survive. The run is blocked until you resolve it.

This blocks the whole run, not just the affected rows. That is deliberate: a conflict means a proposal is wrong, and the rows around it were proposed by the same matcher.

Why it is a block rather than a warning

The outcome of processing two files into one destination is not partially correct, it is silently wrong. One document ends up live and the other is gone, with no error anywhere, and which one wins depends on the order rows happened to be processed in. There is nothing to recover from afterwards except a backup and a guess about what should have been there.

The check runs on every chunk of the run, not just the first — a guard the caller can decide to skip is advisory rather than enforced.

How to resolve it

Use the Conflicts filter on Review & Resolve to see just the affected groups. For each one:

• One of them is the right file. Set the others to Skip, or delete them if they were uploaded by mistake.
• They belong to different posts. Reassign the wrong one to its correct post. This is the common case: two similarly named documents matched to the same page because their names are close.
• They should be one document. If Combine is enabled and they are PDFs, merging them makes one row and resolves the conflict. The originals are kept, marked Combined.
• You are not ready to decide. Skip them all and run the rest; they stay in the batch for later.

The block clears as soon as no two eligible rows resolve to the same destination.

The other kind of sharing

A separate message says a file is shared with a post outside the batch. That is a different situation with a different answer, and it refuses only the affected rows rather than the run.