Duplicacy-web storage graphs don't add up

I’m confused about what the “ALL” line represents on the graph of the duplicacy-web STORAGE pane. Why doesn’t it add up to the sum of the individual storage lines, and how does it dip below them?

[edit: I figured out how to delete the last revision. Still wondering about the ALL line though]

Thanks!

Because of deduplication.

That’s a bug.