MVC Multiple File Upload with Additional Data

First create 2 ViewModels

public class NewViewModel 
{
    // list of files with additional data
    public List<UploadItem> UploadItems { get; set; }

    public string AnotherPropForView { get; set; }
}

public class UploadItem
{
    // your additional data
    public string CustomProp1  { get; set; }
    public string CustomProp2  { get; set; }
    // file
    public HttpPostedFileBase UpFile { get; set; }
}

Create controller. One action for display empty form and second for process data from view.

public class SomeController : Controller 
{
    public ActionResult Create() 
    {
      NewViewModel model = new NewViewModel
      {
         // inicialize list
         UploadItems = new List<UploadItems> 
         {
            // inicialize empty objects ( if you want to have 2 file fields with additional data)
            // or inicialize only one object and another fields add by Javascript
            new UploadItem {},
            new UploadItem {},
         }
      }
      return View(model);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(NewViewModel model) 
    {
        // if (ModelState.IsValid) etc...
        foreach (var uploadItem in model.UploadItems)
        {
            // work with file and additional data
            var file = uploadItem.UpFile;
            var prop1 = uploadItem.CustomProp1;
            // file.SaveAs("/some/where"); atc ...
        }

        // return some view...
    }
}

And create view

@model Path.To.NewViewModel
@using (Html.BeginForm("Create", "Some", FormMethod.Post, new { enctype = "multipart/form-data" }))
{
@* Print all inicialized upload items *@
  @for (int i = 0; i < Model.UploadItems.Count; i++)
  {
    @Html.TextBoxFor(model => model.UploadItems[@i].CustomProp1)
    @Html.TextBoxFor(model => model.UploadItems[@i].CustomProp2)
    <input type="file" id="UploadItems[@i].UpFile" name="UploadItems[@i].UpFile" />
  }

<button name="Action" type="submit" value="Save" class="btn">Save</button>
}

You can use Javascript for dynamic adding Uploaditem to form - you have to generate right index to name and ID property in inputs