Multiple Burns on a DVD?

I use an iMax with Snow Leopard. Could someone tell me if it is possible to burn info on a recordable DVD more than once (add info to the original DVD)? I found that I can do this with Disk Utility but, apparently, only using CDs, not DVD disks. Thanks.

Toast can do that, just so long as you don't finalize the disc.

Also, let's move this one to the right forum....