Are they dvd video? If so, I think the first ISO would play, but the second one would not.
Assuming that they are dvd video, and you don't mind losing the menus, you could combine them into one video, and make a new, simple menu to select each video.
Mount each ISO in VirtualClone Drive (you can have more than one virtual drive extant in your computer). Import the dvd videos into AVStoDVD and make your menu. Make certain to set the video and audio encoding to retain dvd compliant streams without reencoding them. Also make certain to set output size to DVD-9 (double layer dvd).