Getting Array From An ArrayList

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C#

ArrayList al = new ArrayList();

string name="my name is tanzeel and my complete name is TANZEEL ahmed"

for (int i = 0; i < name.Length; i += name.ToLower().IndexOf("tanzeel") + 7)
{
    int a = name.ToLower().IndexOf("tanzeel", i);
    al.Add((string)(name.Substring(a, 7)));
}

now in this program i have stored the name tanzeel as it is in the string since in my string it comes 2 times one with small letter tanzeel and other starting with capital letter. so i have stored them as it is in an array. now i want to replace the same word from an array means first time a word with small letter tanzeel and then where it finds TANZEEL should replace with starting with capital letter TANZEEL as stored in an array. Is there any way?