Hey @John_Nyvelius ,
It appears that you want to avoid duplicates, in that case, you could create some type of database where you would store information about published articles and search through it to see if the RSS article was already published. Make has Datastores, that can help in storing the data which then can be used in Filtering.
You can try to filter based on the published date something like this:
I hope this is helpful.
Thanks.