Yes. Debian has its own restrictions on one of its own logos. See the terms on their restricted use logo on their Logos page[1]; they reserve the right to assert copyright privilege in the same way.
(BTW, copyright and trademarks are very different things, be careful with your terminology.)
You're right that copyright and trademark law are two different things. That said, the word "trademark" occurs on that page only in the footer, applied to the name Debian. Nowhere (on that page at least) are the images asserted as trademarks, whereas there's a prominent copyright notice near each logo. I suppose the copyright could be read to apply to the license text and not to the logo, although that would be odd, and inconsistent with the explicit copyright wording of the open use logo.