1) No. It should be 2 different pages.
You can find a lot of examples among 2-sides advertising and marketing platforms which use 2 different buttons for each proposition.

For example for ad platforms:
- For advertisers;
- For Publishers.

So you can use similar approach. Just choose one of them:
- add services to nav bar of the main page;
- or add 2 buttons with bright CTA on page.

in your case:
- For buyers;
- For photographers.

2) In terms of SEO...
My personal advice - never think about SEO.
Think about:
- Good product;
- Good content;
- Right user experience.

If everything is good, it generates huge positive behavioral factors which impact search engines.

2 value propositions on the same page is a bad user experience. So it's bad for SEO too, because it has worse conversions.

Think in terms of people, not in terms of algorithms and machines.