Ajax begin form db record with mvc - asp.net-mvc

Question

I created a form. I want to do a post save method.
He records but records the same data twice. How can I solve this problem?
I have to solve the double registration problem. I'm pushing the button once. When I go through Debug step by step, it goes twice on the same line. When I control the db as a top-down, I see that you double-logged.
HTML:
<div class="portlet-body form">
#using (Ajax.BeginForm("TalepTurKaydet", "MasterEducationController",
new AjaxOptions { HttpMethod = "post", OnSuccess = "TalepTurKaydet" },
new { #class = "" }))
{
#Html.ValidationSummary(true)
<div class="form-body">
<div class="row">
<div class="col-md-12" style="margin-left: 20px">
<div class="col-md-6">
<div class="form-group">
<label class="control-label col-md-3">Açıklama: </label>
<div class="col-md-9">
<textarea id="Aciklama" name="Aciklama" class="col-md-12" style="resize: none;" rows="5" placeholder="Açıklama"></textarea>
</div>
</div>
</div>
<div class="clearfix"></div><br /><br />
</div>
<div class=" form-actions right">
<button type="button" class="btn green btnPrevious"><i class="fa fa-angle-double-left"></i>Geri</button>
<button id="talepOlustur" type="submit" class="btn blue"><i class="fa fa-check"></i> Talep Oluştur</button>
</div>
</div>
}
</div>
Controller:
public ActionResult MezuniyetBilgiKaydet(MezuniyetBilgi model)
{
List<MezuniyetBilgi> list = null;
model.KullaniciId = GetUye().kullaniciID;
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(ApiAdress.API_URL);
var responseTask = client.PostAsJsonAsync("apiMasterProgramEducation/MezuniyetBilgiKaydet", model);
responseTask.Wait();
var result = responseTask.Result;
if (result.IsSuccessStatusCode)
{
var readTask = result.Content.ReadAsAsync<List<MezuniyetBilgi>>();
readTask.Wait();
list = readTask.Result;
model = list.FirstOrDefault();
return Json(new
{
Success = true,
data = model,
Message = SuccessMessage.MEZUNIYET_BILGISI_INSERT_MESSAGE,
JsonRequestBehavior.AllowGet
});
}
}
}
API:
public IHttpActionResult MezuniyetBilgiKaydet(MezuniyetBilgi model)
{
List<MezuniyetBilgi> detay = new List<MezuniyetBilgi>();
try
{
using (var ctx = new ktdbEntities())
{
if (model != null)
{
var query = ctx.mezuniyetBilgisiEkle(model.KullaniciId, model.MezuniyetTarih, model.MezunOlduguOkul,
model.MezunOlduguFakulte, model.MezunOlduguBolum, (float)(model.MezuniyetNotu));
model.Output = true;
detay.Add(model);
return Ok(detay);
}
}
}
catch (Exception e)
{
model.Output = false;
model.Message = e.Message;
detay.Add(model);
}
return Ok(detay);
}