Duplicacy storage amount not matching actual storage amount

I’m backing up to Backblaze. Backblaze states I’m using 1,162.6Gb. this is the only service I have using backblaze

However, Duplicacy states my storage usage on Backblaze is 700.74G

I have run an -exaustive purge.

Any idea why these numbers are so different? is there a way to clean it up, short of clearing out the bucket and trying again?