title: Multer uploads different files from differents inputs but from the same form
body: <p>I looked everywhere on internet but I found nothing that looks like my issue.
  I'm new to Node.JS and I want to upload, with Multer, two different pictures but from the same form. Here's my form: </p>
  
  <pre><code>&lt;form action="/upload" enctype="multipart/form-data" method="post"&gt;
      &lt;label for="pp_uploader"&gt;Add a profile picture&lt;/label&gt;
      &lt;input type="file" id="pp_uploader" name="pp"/&gt;&lt;br&gt;
      &lt;label for="banner_uploader"&gt;Add a banner&lt;/label&gt;
      &lt;input type="file" id="banner_uploader" name="banner" /&gt;&lt;br&gt;
      &lt;input class="sbutton" type="submit" value="Envoyer" /&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>Here's the code:</p>
  
  <pre><code>app.post("/upload", function(req, res, fields) {
  
    const storagepp = multer.diskStorage({
      destination: "data/pp/",
      filename: function(req, file, cb){
        cb(null, sess.surname + sess.name + ".jpg");
      }
    });
    const uploadpp = multer({
      storage: storagepp
    }).single("pp");
    uploadpp(req, res, (err) =&gt; {
      if (err) throw err;
    });
  
    const storagebanner = multer.diskStorage({
      destination: "data/banner/",
      filename: function(req, file, cb){
        cb(null, sess.surname + sess.name + ".jpg");
      }
    });
    const uploadbanner = multer({
      storage: storagebanner
    }).single("banner");
    uploadbanner(req, res, (err) =&gt; {
      if (err) throw err;
    });
  })
  </code></pre>
  
  <p>And I'm getting this error: </p>
  
  <pre><code>Error: Unexpected field
      at makeError (/home/quentin/Documents/SocialHorse/node_modules/multer/lib/make-error.js:12:13)
      at wrappedFileFilter (/home/quentin/Documents/SocialHorse/node_modules/multer/index.js:40:19)
      at Busboy.&lt;anonymous&gt; (/home/quentin/Documents/SocialHorse/node_modules/multer/lib/make-middleware.js:114:7)
      at Busboy.emit (events.js:160:13)
      at Busboy.emit (/home/quentin/Documents/SocialHorse/node_modules/busboy/lib/main.js:38:33)
      at PartStream.&lt;anonymous&gt; (/home/quentin/Documents/SocialHorse/node_modules/busboy/lib/types/multipart.js:213:13)
      at PartStream.emit (events.js:160:13)
      at HeaderParser.&lt;anonymous&gt; (/home/quentin/Documents/SocialHorse/node_modules/dicer/lib/Dicer.js:51:16)
      at HeaderParser.emit (events.js:160:13)
      at HeaderParser._finish (/home/quentin/Documents/SocialHorse/node_modules/dicer/lib/HeaderParser.js:68:8)
  </code></pre>
  
  <p>When I use <code>console.log(fields);</code> I'm getting this: <code>[Function: next]</code></p>
  
  <p>I also tried to upload only one picture with only one input in my form and it seems to work so I'm probably missing a function which is able to done my work.</p>