What sort of data are we talking about? Whichever, the answer is yes.
If it's video, sure. You can use something like MakeMKV/Handbrake to get the video from the disc and then something like Brasero or K9Copy to create the new DVD. You'll lose quality but there you go.
If we're talking about files then there's really no option to reduce their size significantly but you should be able to break them up into multiple files. If you have files that are too large to fit on a single disc, there are tools like hjsplit that will allow you to dismantle them, put them on disc, copy them off discs at the other end and then reassemble.