I have the same problem on my Sony GX120 DVD recorder. I'm sorry to say it seems to be a nasty bug in the machine's firmware. Almost every time I record a DVD, at least one "empty title" appears in the track list, only after I've finalised the disc. On one disc I accidentally recorded a section with nothing in it. Despite deleting this before finalisation, when I viewed the finished disc, there were two "empty titles"!
I can't see anything I'm doing that would cause this, or any obvious way to avoid it. Annoying as it is, my guess is that only Sony could fix it by issuing revised firmware for the machine. Unless anyone knows better...?