Old Posts/Same Posts Repeating

Hello, Using both Newsomatic and the Echo RSS Feed Post Plugins I see the same posts repeatedly every time the plugin calls the feeds.  I send them to the trash and next time I check, the same posts appear again. Also, old posts from days and sometimes weeks are showing up. Now, I am probably blind but looking at both main settings and feed settings for both plugins, I cannot find any option to disable old posts. Help please.