(My field is Computer Science, where conference publications are the norm.)
I reviewed a paper submitted to conference A six months ago. The paper was borderline, and was eventually rejected. I wrote a reasonably lengthy review.
I've now been asked to review a re-submission of the same paper from the same authors for conference B. At first glance, the differences between the versions A and B are quite minor.
While I would have no problem reviewing the re-submission, I am worried about any bias (real or potential) that could occur from having access to a previous version of the work. This may be seen as preventing version B from standing on its own merits and having a "fair" shot at this conference.
It's possible that my review of paper B will have the same comments as paper A, or at the very least my review will be written in a similar style. As such, while the reviewers are anonymous, it's quite possible the authors will realize the same person reviewed the two versions of the paper.
Should I accept this review, or suggest an alternative referee?