I'm not certain it is "duplicate" as again, the backup amount (1.07 GB) is roughly half of the amount on the iPhone.
Does WhatsApp have settings for syncing with iCloud (or WhatsApp) as well as "Chat Backup"?
So, you recently were in an out-of-storage situation with iCloud, and you deleted messages (or more likely videos) to bring things back down below 5 GB in iCloud? That could explain things - the WhatsApp archive may still be in the process of syncing now that there's storage space available. Keep watching the numbers. If the amount in Settings > Apple ID > iCloud > Manage Storage keeps going up while the amount in Settings > Apple ID > iCloud > Manage Storage > Backups > [this iPhone] > Info goes down, then things probably just need more time.
Or not. Again, I don't know WhatsApp in specific, just iCloud in general.
Overall, what you can expect is that if there's 2.02 GB in Settings > General > iPhone Storage, then you'll be using at least that much in iCloud, whether it's split into two categories (as it is currently), or whether it's all in one category.
If WhatsApp uses iCloud as Apple intends, then when all WhatsApp data on your phone has fully synced to iCloud, you should not see WhatsApp as a significant part of backup - most or all the data should be found in the Manage Storage setting page.