I am confused about this rule

Rule 1: “Do not submit mirror sites”

Is this means:
(1) if I have two identical sites, I can suggest one and only one of them, OR
(2) if I have two identical sites, I cannot suggest any of them at all.

Which one?

Thanks.

(1) One. Suggest one.

Anecdotally - I came across a firm with 168 sites of which all, bar a few, were more or less the same (yes I checked them all ).

They had however only ever submitted one.

Folow their shining example.