Can't force LINQ evaluation - linq

Question

I'm trying to get a record and store it for later use if an error occurs on the page.
This code is used on Create/Edit. So I'm getting values from a View Model and mapping to the db entity:
Dim objExistingSupplier As SUPPLIER = db.SUPPLIER.Single(Function(e) e.SUPPLIER_ID = Supplier.SUPPLIER_ID)
objPermStaffAction = objExistingSupplier
objSupplier = Mapper.Map(Of SupplierViewModel, SUPPLIER)(Supplier, objExistingSupplier)
From what I understand, the .Single should force evaluation. However, after the mapping occurs properties are lost/changed in the objPermStaffAction object. Can someone explain what I'm doing wrong?
Here is the whole function:
Private Function SaveSupplier(Supplier As SupplierViewModel) As ActionResult
Dim objSupplier, objPermStaffAction As SUPPLIER
If Supplier.SUPPLIER_ID = 0 Then
objSupplier = Mapper.Map(Of SupplierViewModel, SUPPLIER)(Supplier)
Else
Dim objExistingSupplier As SUPPLIER = db.SUPPLIER.Single(Function(e) e.SUPPLIER_ID = Supplier.SUPPLIER_ID)
objPermStaffAction = objExistingSupplier
objSupplier = Mapper.Map(Of SupplierViewModel, SUPPLIER)(Supplier, objExistingSupplier)
End If
If ModelState.IsValid Then
If Supplier.SUPPLIER_ID = 0 Then
objSupplier.CREATED_BY = Session("AppUserID")
db.SUPPLIER.Add(objSupplier)
Else
objSupplier.UPDATED_BY = Session("AppUserID")
UpdateModel(objSupplier)
End If
Try
db.SaveChanges()
Return RedirectToAction("Index")
Catch ex As Exception
If InStr(ex.InnerException.InnerException.Message, "PRSNL.SUPPLIER_UK") > 0 Then
ModelState.AddModelError("SUPPLIER_CODE", "Supplier Code already exists. Please choose another.")
End If
End Try
End If
'This will run if an error occured
If Supplier.SUPPLIER_ID > 0 Then
Supplier = Mapper.Map(Of SupplierViewModel)(objPermStaffAction)
End If
ViewBag.YNList = Common.GetYNList
Return View(Supplier)
End Function

Answer 1

SupplierViewModel is reference type. So objPermStaffAction refer to the same object which is getting updated after mapping.
Why do you need original (not mapped) object?