I'm going to have to agree with Zig on this. There's no CONFLICT here, just commonality. Lawyers often make their living representing multiple clients suing a common defendant. As long as this situation doesn't put one client at a disadvantage over the other, there's no conflict, just mutual benefit perhaps. There's a whole cottage industry representing a slew of clients involved in suing particular defendents be they drug companies, or the government, or auto manufacturers, or investment banks, etc...
Further, were there a conflict between his two clients, that's no business of yours. They'll have to raise that issue themselves if they want.
A standard part of such representation is almost always disclosure of any potential conflict to the new client. As Zig says, I'm sure the attorney has cross his eyes and dotted his tea.
