retaining values of a list

List<SampleData> samples = new List<SampleData>() 
{
new SampleData { Value1 ="1", Value2="1001", Value3 = null, Value4 = true},
new SampleData { Value1 ="2", Value2="1002", Value3 = "5002", Value4 = false},
new SampleData { Value1 ="3", Value2="1003", Value3 = "5003", Value4 = true}
};
  
List<SampleData> samples2 = new List<SampleData>() 
{
new SampleData { Value1 ="1", Value2="1001", Value3 = null, Value4 = true},
new SampleData { Value1 ="4", Value2="1002", Value3 = "5002", Value4 = false},
 new SampleData { Value1 ="5", Value2="1003", Value3 = "5003", Value4 = true}
 };

List<SampleData> samples1 = samples2;
foreach (var item in samples)
{
samples2.Where(s => s.Value1 != item.Value1).ToList().ForEach(t => { t.Value4 = true; });
}


public class SampleData
{
public string Value1 { get; set; }
public string Value2 { get; set; }
public string Value3 { get; set; }
public bool Value4 { get; set; }
}