Here in the printer’s manuscript, Oliver Cowdery initially wrote “he did as the Lord commanded him”; then he supralinearly inserted according and had (with the same level of ink flow), giving the final text: “he did according as the Lord had commanded him”. There is nothing grammatically wrong with “he did as the Lord commanded him”. Thus the corrected text undoubtedly represents the reading of the original manuscript, which is no longer extant here.
The phraseology “according as” is unusual in modern-day English and may be considered somewhat redundant. Nonetheless, the Book of Mormon text contains 21 occurrences of this expression (and the King James Bible has 33). In fact, there are seven other occurrences of “according as” where the following clause contains the past perfect auxiliary had:
Thus there is nothing wrong with the corrected reading for Omni 1:13 in the printer’s manuscript.
Summary: Retain in Omni 1:13 the expression “he did according as the Lord had commanded him”, Oliver Cowdery’s nearly immediate correction to the reading of the original manuscript.