SEO help: Should I put two of the same types of companies at the same address?

I do SEO for a roofing company and the business owner just told me he's having his brother move into his office. His brother has his own roofing company as well. So two roofing companies 1 office.

I remember reading an article back in the day where a dentist had trouble ranking in Google because he moved into an office with another dentist.

I'm suggesting to avoid this, do you agree with me in this situation? for these reasons I concluded:

#1. with his brother moving in, his brother would have to fix his NAP all over the internet.

#2. his brother would lose local map pack rankings from his current location. Because if he moves into the exact office they would be competing for the same map pack rankings.

But here's the thing, his brother is probably going to update his roofing website to my current client's address. So it will be two roofing companies at the same address.

Granted yes, they will have different SUITE numbers, i'm wondering if this will cause problems. I don't want to see either of them lose website leads over this.