Based on the wording, it’s the Dell settings.
Veeam BP states that Veeam’s categories are “integrated” and “non-integrated”, interestingly it defaults to dedupe-friendly which breaks our documentation stalemate! But further to this, KB1745 is general dedupe appliance best practices. Veeam specifically state to check vendor documentation, which should supersede Veeam’s guidance in the KB.
If in doubt and you have the time, raise a case with both Dell & Veeam, I would go for the Dell settings otherwise, will save you the painful troubleshooting with Dell if you need to raise a case with them!
BP Article Link:
https://bp.veeam.com/vbr/3_Build_structures/B_Veeam_Components/B_backup_repositories/deduplication.html