I would retain only the corrected minutes of the first meeting and note in the minutes of the second meeting that the first minutes had been approved as corrected.  I don't see any more need to keep the incorrect minutes than I see a need to keep the Secretary's drafts before the version that was presented for approval.

If the organization maintains a complete copy of everything given to the Board in connection with each meeting, the incorrect minutes would be in the package for the second meeting.  But I would keep only the corrected minutes in the Minute Book.  Ultimately, it probably does not make much difference as long as the correct minutes are clear, but it is less confusing to have the correct minutes in a single document.  (See Ready Reference Page: “Preparing Minutes of Board Meeting is Usually More Art Than Science.”)