Is there a way of completely cloning a DVD on a Mac? True 1:1 copying?

A video DVD?

Something like MacTheRipper will copy all the contents from the DVD to your hard drive and it still acts like a DVD...Otherwise Disk Utility can copy it to an iso/dmg file...

I've used Disk Utility to save it as a DMG, so can I then just burn the contents to a blank DVD? Yes video.

I've used Handbrake which I love but I was wondering if I could do it in it's entirety.

Yeah, use MacTheRipper, or alternatively, you can try Fairmount (you'll need VLC installed though) - Clicky.
MacTheRipper is good though.

You could also try DVD2oneX2 which I've only used once, in an emergency, but it may be what you need.