ASP.NET MVC MultiSelectList with selected values not selecting properly

I know others have asked this question, but I'm totally confused by this:

This displays the dropdown with no values selected:

<%= Html.DropDownList("items", new MultiSelectList(Model.AvailableItems,
    "id", "name", Model.items), new { multiple = "multiple" })%>

This displays the dropdown with the values that I'm passing in (Model.items) selected properly like what I'd expect:

<%= Html.DropDownList("somethingelse", new MultiSelectList(Model.AvailableItems,
    "id", "name", Model.items), new { multiple = "multiple" })%>

But the problem is that this item is now named "somethingelse" when i POST. I know I can hack around this but what's going?