Macbook Pro burns DVD+R DL - but isn't supposed to be able to?

Question

Not your typical post - I've actually had something WORK, but now am wondering why...
Started a burn job to a dual-layer DVD+R disc, and while waiting on it, it occurred to me that maybe my Macbook Pro doesn't support +R. So I looked at system profiler, and +R does in fact NOT show up as a burn capability.
Is there a chance I'm causing damage to the drive, trying to do this? I would think that if it was incompatible, Toast would have spit it back out.
(BTW, I have yet to see any DL DVD-R disks for sale from the usual retail suspects; does such a thing exist, or are DLs strictly a +R thing?)

Answer 1

Your MBP should be able to burn CD-R, CD-RW, DVD-R, DVD-RW, DVD+R, DVD+RW, and DVD+R DL. Go to the /Applications/Utilities folder and run System Profiler.app. Click on "Disc Burning" in the list, and you should get information about the capabilities of your writer.
You're not causing any damage to the drive.
There are DVD-R DL disks out there, however, it doesn't appear to be a very popular format. In my experience, the DVD-R DL format (writing not supported on the Mac) is so-so reliable on computer, but far less reliable in set-top DVD players.
One thing that get me, though, is that iDVD appears to not be able to burn DL disks. That's a serious shortcoming.