Can you dupicate DVD-9?

There is a difference between DVD-9 and double layer DVDR - DVD-9 is the dual-layer DVDs that are replicated (pressed). Double layer DVDR are actually a blank DVD media that contains 2 layers.

With double layer blank DVDs (abbreviated as DL DVDR here) it allows longer videos to be placed on a single DVD. Is it possible to duplicate a DL DVDR like a regular single layer DVD? While DL DVDR has been around for a little while, there are not many choices in the brand of media, and some media tend to have compatibility issues in older players. We would suggest against making mass duplication of a DL DVDR master; instead opt to compress the entire disc to a single layer DVD for DVD duplication, or split the content onto a 2-disc set.