The item title, URL and published time are all provided by the feed publisher, and are therefore of variable quality
I've seen feeds where every item has the same URL, or no item has a title nor URL! So, it's possible that the channel is, in fact, publishing items with the same title and/or URL and/or timestamp.
However, what's probably happening here is "item revisions". These happen when Awasu receives an item, and the publisher then changes something (e.g. fixes a typo in the content), and Awasu receives the new version. By default, Awasu only shows the most recent revision, but you can configure it to show all received versions (Track revised items
in the Advanced tab of the channel's Properties dialog). Awasu does delete these old revisions eventually, but there is a window of time where an item has multiple revisions stored in the archive database, which might be what you're seeing here.