Property values of the same type are updated incorrectly in Blazor - asp.net-core

Question

Background:
I wanted to achieve the following:
Keep a copy of the data context and use the copy for editing
So that I can reset the data context back to its unchanged state using an onclick event by doing copyValue = unchangedValue
Here is my attempt (it's been trimmed down in size to reduce noises but it has the same issue):
**index.razor**
#page "/"
#using SolutionName.Data
#using System.Reflection
<EditForm Model="Items2">
<table class="table">
<thead>
<tr>
<th>Summary</th>
</tr>
</thead>
<tbody>
#foreach (var i in Items2)
{
<tr #key="#i.GetHashCode()">
<InputText #bind-Value="i.Summary"></InputText>
</tr>
}
</tbody>
</table>
</EditForm>
//
//reflections for debuggings
//
#if (Items != null)
{
<p>
#foreach (var item in Items)
{
<span>#($"Items.{typeof(WeatherForecast).GetProperty(nameof(WeatherForecast.Summary)).Name}={typeof(WeatherForecast).GetProperty(nameof(WeatherForecast.Summary)).GetValue(item)}")</span>
}
</p>
}
#if (Items2 != null)
{
<p>
#foreach (var item in Items2)
{
<span>#($"Items2.{typeof(WeatherForecast).GetProperty(nameof(WeatherForecast.Summary)).Name}={typeof(WeatherForecast).GetProperty(nameof(WeatherForecast.Summary)).GetValue(item)}")</span>
}
</p>
}
#code{
List<WeatherForecast> Items = new List<WeatherForecast>();
List<WeatherForecast> Items2 = new List<WeatherForecast>();
protected override void OnInitialized()
{
Items = new List<WeatherForecast>()
{
new WeatherForecast()
{
Date = DateTime.Now,
Summary = "123",
TemperatureC = 1
}
};
Items2 = Items;
}
private void ResetItems2()
{
Items2 = Items;
}
}
As you can see, I am binding Items2, and not Items, to the <EditForm>.
However, updating the summary seems to update both Items2 and Items. I also noticed that this will not happen if Items and Items2 are of two different types (say that they have exactly the same properties, and I cast one to another...)
Two questions:
Why is Item updated in this case?
Is there a way to only update Items2 and not Items, while allowing Items and Items2 to be the same type?
Detailed steps to reproduce the issue:
Step 1. Initialized and render for the first time
Step 2. Change the value to 456 and then tab away
The expected result should be
Items.Summary=123 (not 456)
Items2.Summary=456

Answer 1

The issue is that you're using reference type assignment. When you assign Items to Items2, you actually assign a pointer to Itemss values. Both variable point to the same list of objects.
If it's applicable create a value type instead. Saving data in the local storage and then retrieving it is a viable solution.
This:
List<WeatherForecast> Items = new List<WeatherForecast>();
List<WeatherForecast> Items2 = new List<WeatherForecast>();
is superfluous. Code like this:
List<WeatherForecast> Items;
List<WeatherForecast> Items2;