According to this Q article, what happened is that a successful backup of Wins was not done and therefore multiple logs were created. So I guess we just need to restart the server if this happens again.
"The log files are processed (all log entries written to the database) and deleted when a successful backup occurs or when the WINS server is shut down gracefully. Therefore, if many J.log files have accumulated, frequent backups should be scheduled to maintain the logs.
After the entries have been processed, it is possible to manually delete the log files; however, this will prevent a successful recovery of the database if it should be needed. Because of this, it is important to ensure that the log files are not manually deleted or removed from the system until a backup has been performed. "