No, it's a point to point ticket with both stations clearly printed on the ticket. If you decide that you wish to travel to ED, you'd have to technically get off the train, buy another ticket (not recommended)s or go out of the gates at PR, then use a pay as you go Oyster card to touch in. I'm sure if you went to the London Bridge ticket office, tell them you want to go to ED but have a ticket to Peckham Rye, they should be able to sell you a single from PR to ED without having to leave the train. I've done this at East Croydon when I've had to travel up to Victoria but only had a zones 1-4 travelcard. You'd be better off with a zone 1-2 travelcard if you decide to travel like this regularly.