Can I mention interest in two somewhat different research areas in my SOP?
Stop calling it an interest when you have publication proving expertise. I'm "interested" in the Real Housewives show. You need to find a better set of verbiage. You are at the edge of the field in two areas but it remains one field. Let the professors fight over who gets to work with you. Let them fight over who gets published with you. You need more than one vote to get in, so get all votes. You are accomplished in two areas of one field. Show that you are young and scrappy and willing to do the work and they will put you to work wherever they see fit. I'm wondering if current students "do their own thing" or basically apprentice on professor pet projects and publish for the professors. See what has been published. They want someone to do the work and keep the school top tier, but they don't need any competition later, right? Focus on what an honor it would be to be mentored by them at such a great place. They have to actually work with you and sit for office hours with you, so be that guy who gets the work done between meetings and isn't needy yet takes all suggestions and is deferential.