Bruno Frey, one of the better known economists in the German speaking world, has apparently published quite similar papers in different journals on multiple occasions, all without cross-citation.
This is bad behavior, though I think there are some nuances that the blog post at the link does not touch on. I would argue, for example, that if one uses the same data set in multiple papers, there is no harm in using the same data description, and without any cross-citations. I think the harm comes when it is the results that are being recycled, rather than just boilerplate about data or treatments or estimators or whatever. I can also imagine cases where the world is a better place if similar papers appear in, say, an economics journal and a statistics journal, so long as there is cross-citation and the papers are appropriately targeted to their respective audiences. Getting people to read across disciplinary lines is tough, and a bit of documented repetition (and, in the short run, a few extra dead trees) may be worth it to get them to do so.
It's really quite easy.
1 year ago