New user with same username as deleted user gets falsely attributed with comments and work logs

James - one of the developers in here just found something a bit strange and slightly scary in Jira.

A few years ago we had a guy called Michael Treanery (user name: michael) working here. When he left in 2005 we moved all his issues to his replacement and closed/deleted his account.

We recently hired a new guy called Michael Osborne (user name: michael).

Today James was browsing through some issues and he found that comments and work log entries dated back in 2005 were being attributed to Michael Osborne. We are assuming this is because of they shared a user name.