Without a menu you can use DVD2One with join mode. Or I think Nero Recode will do it..............or is it vision express.............one or the other...........
Also, without a menu, you can use DVD Shrink and bbmayo's guide http://home.comcast.net/~bbmayo/join2movies.htm
There's a lot of programs out there.. I think the Nero/Shrink in re-author mode is one, of the easy ways. http://www.dvdplusvideo.com/tutorial007.html or http://home.comcast.net/~bbmayo/join2movies.htm easy guide written by a pair of great guys' gringle..