不解为何这段代码里有exports，module.exports同时存在？

var logger = require('../common/logger');

module.exports = function (req, res, next) {
  // Assets do not out log.
  if (exports.ignore.test(req.url)) {
    next();
    return;
  }

  var t = new Date();
  logger.info('\n\nStarted', t.toISOString(), req.method, req.url, req.ip);

  res.on('finish', function () {
    var duration = ((new Date()) - t);

    logger.info('Completed', res.statusCode, ('(' + duration + 'ms)').green);
  });

  next();
};

exports.ignore = /^\/(public|agent)/;

这是本站源码里的一段 https://github.com/cnodejs/nodeclub/blob/master/middlewares/request_log.js

因为在查看的资料里知道，如果module.exports，exports同时出现，exports的值会被忽略，那这种写法是啥意思？有些不解