Output much bigger then original DVD...

[Cyruz]

Hello!
I'm all new to mkv, but thougt I might start using it instead of iso, that I've used before...

But when I first try to make an mkv (from finding nemo, DVD) I end up with files totaling a lot more than the files on the DVD..
The main title seems right (about 4.8 GB, 32 chapters) but then I get another title thats about 6.4 GB, and 93 chapters....
The second title seems to be something like "the makin of finding nemo" and it seems to be the complete movie with the directors cutting in and showing how they made specific animations and stuff like that, so my question is, can this second title actually somehow be smaller on the original disc, but contain "links" to the main title???

Thank you in advance for helping a novice...

[Cyruz]

Ah, found the answer, it turns out different titles on the original disc can share some content, just as i suspected.