Do they both use standard mini or micro USB for charging? And are you talking about charging them while on the move or just a top up while you're stopped somewhere? Not sure it's possible (or advisable) to charge an intercom while you're on the move but the camera should be fine.
Any decent power bank that can charge more than one device at a time should work if combined with a couple of decent charge cables of the right type, I'd recommend Anker as probably one of the best brands to go for. I have one for my phone/tablet for when I'm travelling on business (remember when people used to do that?) and it'll charge my phone multiple times.
Phil