The additional and introduced by the 1830 typesetter appears to be a typo, although it may have been consciously added. The 1908 RLDS edition removed this intrusive and, but the LDS text has maintained it. The parenthetical nature of the that-clause could be shown better by surrounding the clause with dashes rather than the commas of the printed editions:
and it came to pass that when Laban saw our property
—that it was exceeding great—
he did lust after it
By avoiding the additional and, the text flows better.
Summary: Remove the secondary and that the 1830 typesetter added in 1 Nephi 3:25.