I have come across a number of research papers related to my discipline which were just duplication of previously published work, purposely crafted to appear genuine work. I believe the same is prevalent in other disciplines as well. I see that as Hidden Plagiarism which apparently none questions, and duplicate research papers keep on piling up, adding no value to the academia and society at large.

How can a researcher ensure that he is not duplicating a previously researched area?

What factors lead a researcher to deliberately reproduce a research similar to past researches?

Should the journals that publish such questionable work be excluded from IS impact factor journals?

Please comment!