I have a fix dictionary key `X` and I want to create a `List<Student>` with this key `X` as `finalResult` where I have `data` from some external source.

In below code I am getting error, `An item with the same key has already been added. Key: X'`. How to fix it?

```
 const string dictKey = "X";
        var finalResult = new Dictionary<string, List<Student>>();

        var data = new Dictionary<string, int> {{"A1!D1", 10}, {"A2!D2", 20}};

        foreach (var (key, value) in data)
        {
            finalResult.Add(dictKey, new List<Student>
            {
                new Student
                {
                    Name = key.Split('!')[0],
                    Section = key.Split('!')[1],
                    Age = value
                }
            });
        }

```