If you want the entire Sonic Underground series, these are the 2 box sets to get. They look very similar, but see that little "Vol 2" on the 2nd one (really they just switch Sonia & Manic positions and change the background....). Each one has 420 minutes of content, and 4 disks. Their listed release dates are usually also a mistake/opposite.

In the gallary are actual photos of the disk boxes (all above is factory art) & you can take a look at the backs, and how they differed. The left has episode summaries, while the right does not. The disks always take a bit of art from the box & print it on there with the logo.