Most likely, it was because the revisor's office decided it was necessary to add a section, but there was already a section next in sequence. For instance, what if you already had sections 1701 and 1702, but logically, something needed to go between the two? At some point, you would renumber all of the statutes, but that is a massive and expensive undertaking. So, some revisors have added a letter to the section to indicate a section in between, so now you have 1701, 1701A, and 1702 in sequence. This is distinguished from subsections, so 1701(A) is section 1701, subsection A. Whereas 1701A is a completely different section from 1701.
For more details, see Section identifiers (LII) from the Legal Information Institute.
