The simple answer is yes.

How you got 3.6 would be interesting, as it is pretty old and I would be hard pressed to tell you where you could get an English version of 3.6 any more. The Get Knoppix link near the top of this page will give you the BitTorrent Link for getting a current copy suitable for CD or DVD in either English or German default language. I would strongly suggest that you use BitTorrent and not use the mirrors and not buy a copy. I also urge you to follow the Documentation link near the top of this page at read, at the very least, the entire Downloading FAQ.

You can also change the language selection as you boot your German copy of Knoppix by typing in a cheat code (if I remember right it is knoppix lang=en but I could be wrong on that and you could check the cheat codes section of the wiki as easily as I and you might even learn a bit in doing that). But that gets to another problem that you have with the German version, not only is the Language German but the Keyboard layout is German as well, so many of the special symbols, including the = siign, are in different places, making it hard to type in the above string! Again just going by a less than perfect memory I think the German = is a shift-zero, but if I'm wrong you may have to search a bit for it.

Oh, if you download a new version of Knoppix be sure to get one with EN in the filename, not one with DE in the name.