Yes. It can copy two DVD movies (DVD-5 or DVD-9) to one DVD-9 under the "Combine two DVDs to one DVD±R DL" copy mode. (If a certain DVD movie is larger than 4.7 GB, it will be compressed automatically). Then a simple menu will be added to the cloned movie for your convenience.
DVD-5 vs DVD-9
At present, there are four kinds of different DVD discs on the market but the DVD-5 and DVD-9 are the most common types to save movie video. Then what are the definitions of them? DVD-5 (single side single layer) can hold around 4.37 computer GB where 1k byte is 1024 bytes. DVD+R/DVD+RW and DVD-R/DVD-RW support this format. This is the most common DVD media, often called 4.7GB Media. A DVD-5 disc will hold normally 133minutes of high quality MPEG-2 encoded video, together with three surround-sound audio channels and four subtitles channels. DVD-9 (single side dual layer) holds around 7.95 computer GB. DVD+R supports this format. This media is called DVD+R9, DVD+R DL or 8.5GB Media. A DVD-9 disc can hold 240 minutes of continuous video. DVD-5/DVD-9 is a complete movie that refers to the media in which it is presented. DVD-5 can be burned to single-sided DVD media and DVD-9 can be burned on dual-layer disks. Here I recommend new software called DVD-Cloner for Mac, the excellent DVD copy software for the Mac operating system. It supports DVD-5 to DVD-5, DVD-9 to DVD9, DVD-5 to DVD-9 formats and can allow you to compress and copy a dual-layer (DVD-9) movie to one DVD-5 disc. What's unique about the software is that DVD-Cloner for Mac is able to split and copy one DVD-9 to two DVD-5s with high quality and combine two DVDs to one DVD. Download the free version and have a try!