Archive of a mail archive: how to disable

We have 130 mail databases.We have an archive policy for some people. There archive dbs are OK, but one has an “archive of an archive”.

How is it possible ? How is it control ? How can I disable this feature (greyed out in Archive settings).

The first archive was originally created in R5, but the second was created in R6.

I am running Domino 6.0.1CF1 and Notes 6.0Fr

Thanks for any contribution on this.