|"I got a reply and someone said the seller reported to them the E in the Dell was not slanted because it was German"|
That's doesn't appear to be true. If you visit the Dell website for Germany here you'll see the logo has a slanted 'E' just like it is on the Dell website for USA & the UK, and probably every other Dell website too:
The DVD you bought is probably not an original, it will be a copy and whoever made it couldn't find a way to print the slanted 'E' on it, expecting that nobody would notice.
If you want a genuine one you should order it from Dell. There should be a link to order one on the specific Dell website for your country.