Asp.net MVC, 4.0 - Ajax, field value is overriden after update - ajax

Question

I am playing around with some ajax, and have experienced a very odd and to me illogical bug.
I am displaying a list of events, wrapped in a form, in a table. Each event has a unique ID (EventID). This is submitted to the action when a button is pressed.
A div surrounding the table is now updated with the partialview that the action has returned.
The problem
When the view is reloaded, all the HiddenFields that contains the field EventID, now cointains the same EventID as. the one that was submitted to the action
I have tried placing a breakpoint in the view, to see what value is put in the HiddenField. Here is see that the correct id is actually set to the field. but when the page updates, all the hiddenfields contains the same eventid as the one originally submitted to the action.
The partialview: _Events
#model SeedSimple.Models.ViewModelTest
<table class="table table-striped table-bordered table-condensed">
#foreach (var item in Model.events)
{
#using (Ajax.BeginForm("AddAttendantToEvent", "MadklubEvents", new AjaxOptions()
{
HttpMethod = "post",
UpdateTargetId = "tableevents"
}))
{
#Html.Hidden("EventID", item.MadklubEventID);
<input type="submit" value="Join!" id="join" class="btn" />
}
#using (Ajax.BeginForm("RemoveAttendantFromEvent", "MadklubEvents", new AjaxOptions()
{
HttpMethod = "post",
UpdateTargetId = "tableevents"
}))
{
#Html.Hidden("EventID", item.MadklubEventID);
<input type="submit" value="Leave" class="btn" />
}
}
</table>
AddAttendantToEvent Action:
[HttpPost]
[Authorize]
public ActionResult AddAttendantToEvent(int EventID)
{
if (ModelState.IsValid)
{
var uow = new RsvpUnitofWork();
var currentUser = WebSecurity.CurrentUserName;
var Event = uow.EventRepo.Find(EventID);
var user = uow.UserRepo.All.SingleOrDefault(u => u.Profile.UserName.Equals(currentUser));
user.Events.Add(Event);
Event.Attendants.Add(user);
uow.Save();
ViewModelTest viewmodel = new ViewModelTest();
viewmodel.events = madklubeventRepository.AllIncluding(madklubevent => madklubevent.Attendants).Take(10);
viewmodel.users = kitchenuserRepository.All;
return PartialView("_Events", viewmodel);
}
else
{
return View();
}
}
How all the input fields look after having submitted EventID 4 to the action
<input id="EventID" name="EventID" type="hidden" value="4">
I am suspecting, this is due to some side-effects from the ajax call, that i am unknown to.
Any enlightentment on the subject would be much appreciated :)