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You can add all the extra restrictions you want, but they effectively won’t do anything. Expecting both the GPL and the additional restrictions to apply is a violation of section 7 of the GPL.

> All other non-permissive additional terms are considered “further restrictions” within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term.

Debian explains this further in their patch file.