Why Html.Hidden won't generate hidden fields with the same name but different value

I am trying to generate a hidden list, so I use hidden fields with same name, however Html.Hidden outputs the existing value instead of new one. So this code...

<% 
    for (int i = 0; i < Model.ProductIds.Count; i++)
    { %>
<%: Html.Hidden("ProductIds", Model.ProductIds[i], new { id=""})%>开发者_StackOverflow社区
<br />
Iteration:<%:i %>
Guid:<%:Model.ProductIds[i]%>
<br />
<% } %>

generates this HTML

<input name="ProductIds" type="hidden" value="48906f4c-1719-43ab-9d7e-c336a71b8624">
<br>
Iteration:0
Guid:48906f4c-1719-43ab-9d7e-c336a71b8624
<br>
<input name="ProductIds" type="hidden" value="48906f4c-1719-43ab-9d7e-c336a71b8624">
<br>
Iteration:1
Guid:b4f01496-dddf-41f2-a05b-43392d779a44
<br>

Note how even though the ids are different, the generated hidden fields got the same value. Why is this happening, and is there any way to work this around?

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I'm not sure why this is happening, but an easy workaround is to just construct the html yourself:

<% 
    for (int i = 0; i < Model.ProductIds.Count; i++)
    { %>
<input name="ProductIds" type="hidden" value="<%:Model.ProductIds[i]%>">
<br />
Iteration:<%:i %>
Guid:<%:Model.ProductIds[i]%>
<br />
<% } %>

---

What is the purpose of a hidden list or multiple hidden fields with the same name? Couldnt you make it a single hidden field with all the values?