The RSS trigger seems to run every flow with an RSS trigger regardless of if the feed provided to other triggers has a new item, the data provided to the flow is also that of the actual triggered flow.
For example i tested with two flows, one with a completely inactive RSS feed and one linked to https://lorem-rss.herokuapp.com which has a new item every minute. When the second RSS feed (https://lorem-rss.herokuapp.com) had a new item both of the flows were triggered and ran with the same info.