Folders show sum of child counts, not actual number of unique items

[ghost]

When the same item appears in multiple feeds in the same folder, viewing the folder shows only one of each item in the list, but the item count shown for the folder in the tree is the sum of counts of all feeds.

[lwindolf]

That's true. At the same time unread count aggregation is one of the most performance costly things in Liferea so it is good to avoid doing more complex calculations (e.g. duplicate elimination).