RePEc carries research in various formats. While journal articles are unique (with very few exceptions), working papers, as they are pre-prints, may be duplicates of listed articles, and they may even appear in different versions, either because they are published in different series, or because there may be updates within a series. We believe that is important to carry all versions, not just the last one, for the following reasons.
- Time-stamps: A working paper allows to establish when some research was conducted and thus determines preeminence of research ideas. Given publication delays in Economics, this can be important.
- Open access: Many journal articles have gated access. Such restrictions can be bypassed by reading working papers, which are mostly open access.
- Link to published version: It is still preferred to use published versions in citations, especially once a paper is accepted in a journal. The originally cited working paper is often linked to its published version.
- Visibility: Working papers are much more read than journal articles, both because they are more current and they are freely available. In addition, working papers are disseminated through NEP.
The process of linking the various versions of the same work is not obvious, however. With about 800,000 works in RePEc, performing matches on titles is a daunting task, especially as fuzzy matching is necessary due to slight variations in punctuation and spelling. For this reason, we do the matching only across the works listed in an author’s profile. This ensures that the likelihood of two works being different versions of the same one to be very close to 100%. But this also means that such matching cannot be done for works where none of the authors is registered, or where a registered authors did not add all versions to the profile, thereby indicating he/she is not the author of this particular version, rightly of wrongly.
In some cases, titles change across versions, or journal editors require a title change. In such cases, a manual link between versions can be added, just contact a member of the RePEc team with the relevant RePEc handles.
The RePEc Blog 
Christian,
thanks for your hint that similar papers with different titles can be linked. I did not know. I have two such cases. How to proceed?
Ekkehart
Ekkehart: we need to obtain the complete RePEc handles of the works to link. Send them to me, Kit Baum or Sune Karlsson.
Christian: It is not obvious to what a “RePEc handle” may refer. Where is it to be found on the page http://ideas.repec.org/a/bla/metroe/v56y2005i2p263-279.html for instance?
For this article, you will find under “publisher info” the following line:
Handle: RePEc:bla:metroe:v:56:y:2005:i:2:p:263-279
On EconPapers, the handle is listed in the bottom right corner, in the border margin.