Here the 1840 edition dropped the subject pronoun he. However, the sentence-initial capitalization of the and in that edition (in fact, in all the editions) clearly shows that the 1840 loss of the he was an accident. The 1837 edition, which served as the copy-text for the 1840 edition, was set as follows:
The compositor for the 1840 edition set the following:
The he dropped out of the 1840 edition because And was set at the end of the line, which led the compositor to divert his eye from the text he was setting. When he started the typesetting for the next line, he apparently thought he had just set the he at the end of line; thus he ended up omitting the he. We may therefore conclude from the accidentals that the omission of the he was not due to Joseph Smith’s editing. Amazingly, the resulting sentence fragment, with its capitalized And and preceding period, has remained in the RLDS text. One would have expected the accidentals to have been adjusted so that the text would have read as follows:
Of course, the correct text has the subject pronoun he (“and he had many wives and concubines and he did cause his people to commit sin”).
Summary: Maintain in Mosiah 11:2 the subject pronoun he (“and he did cause his people to commit sin”) which was accidentally lost during the typesetting for the 1840 edition.