Clear labelling might be the answer

What should journals do about the circulation of “preprints”—drafts of scientific papers that have not yet been formally published? Within the research community they serve several purposes. Some researchers routinely send such drafts to colleagues for their comments. Others use them as an early warning system, to keep colleagues abreast of research that may take months to get into print. Until recently distributing preprints entailed making multiple photocopies of a manuscript and posting them. The advent of faxes quickened the pace but did little to reduce the workload, which effectively limited their circulation. All this has changed with the internet. Draft manuscripts can now be posted on institutional or individual websites. Hundreds of colleagues, instead of a handful, may now see a preprint before its formal publication. Thousands more internet users may be led to a preprint by search engines, which scour the web's pages for key words.

Some journals, such as the New England Journal of Medicine, have come down unequivocally against electronic preprints: “Posting a manuscript, including its figures …