Can two phones with different WhatsApp numbers use the same Google Drive backup? I have 2 phones with 2 different WhatsApp numbers. Both WhatsApp have their Google Drive backup enabled. However, the backup from one phone isn't visible from the other phone, I get the error of &quot;no backup found for this account&quot;.
Can two phones with different WhatsApp numbers use the same Google Drive backup?
No. You can have only one backup on  Google drive
From Drive product forums

Google Drive does not allow multiple Whatsapp backups in the Google Drive, and it overwrites the old one if ever.

Also see WhatsApp FAQ which clearly states that WhatsApp backups are incremental.