[JumpCrisscross]

Would note that when drafting contracts, this is extremely natural to do. You notice you’re reusing a concept and so define it at first mention. Or you write something and later notice an ambiguity. Speaking as a non-lawyer who drafts things from time to time (to be reviewed by a lawyer).

[crazygringo]

Indeed, I find the original to be less ambiguous. Why does the second version refer to payments and benefits in the first sentence, and then give them a name in the second sentence?

In the revised version, I'm now very unclear whether Section 3a payments apply to the first sentence or not. The original makes it crystal-clear that they do; the revised version almost suggests they don't, since they were explicitly added to sentence 2 but not sentence 1.

[s1artibartfast]

They're often supreme Court cases over exactly this issue. Yeah varying definitions in different parts of legislation, which refer to different overlapping scopes or contacts. The court then goes to contextual clues for which reading is better supported. This can be the structural formatting of the legislation, public discourse of the legislature, or logical arguments. Overall, it's usually a mess.

[Izkata]

Not just contracts, this is a variation of an "aside" and I've seen it often enough in books that it's normal to me. I do it pretty regularly in comments here, too.