If one article contains (with same article IDs) in multiple feeds then this article presents in only one feed in the TT-RSS interface and missing in other feeds.
This behavior is an issue if you subscribe an news aggregator like news . ycombinator . com
Do you really want to spam yourself with multiple copies of the same article?
Or are you saying their GUID isn’t really a UID? A plugin to prefix the non-GUID w/ a source name/id could fix that. Or better yet, get the source to comply w/ the standard.
No, the GUID is <guid>; however, if it is missing TT-RSS will take the value of <link>. Because of the way these feeds are structured (the aggregator is missing the GUID) it appears to be the same article to TT-RSS.