Questions about "Disclosure Regarding Real Estate Relationship" form

[Brandon Snyder]

I'm taking a Real Estate Principals class at UCLA Extension and I'm studying for the midterm.  In my textbook there are samples of contracts, and I'm reading them through and through, even the tiny print on the back, and there are two clauses which confuse the hell out of me.

2079.18 reads:

No selling agent in a real property transaction may act as an agent for the buyer only, when the selling agent is also acting as the listing agent in the transaction.

2079.22 reads:

Nothing in this article precludes a listing agent from also being a selling agent, and the combination of these functions in one agent does not, of itself, make that agent a dual agent.

How are these two clauses not contradictory?