I think the question is fairly clear. Someone could have idea A, and write paper A, but then instead of submitting paper A to multiple journals, he or she might re-write the thing into a paper B, but the basic idea is still idea A.
Say the idea is amazing. He or she could then submit paper A to top journal A & paper B to top journal B, and have two top publications from one idea.
This is obviously wrong, and what I describe is extreme, but what would prevent someone from doing this, what would the consequences be? A bad reputation?
There might also be less obvious cases, where parts of a previously published paper are re-used extensively. Is something like this ever o.k. to do? Why don't more people do it? Or am I just wrong in the assumption that people don't do this?
PS: I am coming from a Humanities background, I think in some subjects things like these might be more difficult, e.g. in maths or a paper which describes a certain study / experiment.