I recently refereed a paper for a journal. There were four referees, which for the field in question(number theory), is a lot, especially for a short paper in a minor journal. I recommended a rejection based on a variety of issues. Today I got back a note that the paper had been resubmitted with extensive edits and asked to look at it again. The request to look at it again included the other three referee reports. Here's the strange bit: The referees's reports were not just included but the names as well. This question is not about seeing other referee reports but about seeing their names attached to those reports.
This partial loss of anonymity makes me uncomfortable for two reasons. First, one of the other referees is extremely senior in the field; in fact his review agreed closely with mine, but that certainly wasn't guaranteed. Second, it makes it more likely that a single referee who leaks who they are or knows one of a paper's authors could let the authors know who the other referees are. I wouldn't be so concerned about the second except that I've already had an experience (where I was an author) where a referee unmasked himself after the fact.
My question is then threefold: One how normal is the practice of including their names to the other referees in math? More generally how common is this in other fields? Third, is there a reasonable way to express my concern to the editors?