Avoid concatenating requests when redirecting multiple times in a row

So, I am working in an Express application and am experiencing strange behavior.

I am showing error messages when something is wrong.

/ app / edit / username? E = Error1

It seems that after two errors in the line, the requests are merged somehow:

app / edit / username? E = Error1? E = Error2

I would like this to happen and only display error 2:

app / edit / username? E = Error2

I am using express redirect:

return res.redirect('/app/edit/' + username + '?e=' + error

      

        
        
        
      

    

Any idea on what might be going on?

Thanks a lot in advance and have a nice weekend!

Pablo

edit: part of the function:

User.findByIdAndUpdate(id, update, function (err, user) {
  if (err) {
   var error = dbErrorHandler(err)
   return res.redirect('/app/editar/' + username + '?e=' + error)
  }
  return res.redirect('/app/editar/' + username + '/?suc=upsuccess')
})

      

        
        
        
      

    

and here is the dbErrorHandler:

function dbErrorHandler(err) {
  console.log('There is been an error' + err)
  if (String(err).indexOf('email_1') !== -1)
    return 'eexists'

  return 'unknown'
}

      

        
        
        
      

    

More advice regarding my code is very welcome.