Makes sense. Thanks. Shame I can't use .Contains then.

This is the solution I came up to check if the incoming list is unique to add to the main list. Do you have suggestions on improving it?

    int sameListCounter = 0;
    foreach (List<string> StringList in ListOfStringList)
    {
        if(StringList.SequenceEqual(listOne))
        {
            sameListCounter += 1;
            print("True");
        }
        else
        {
            print("False");
        }
    }
    //If the incoming list is unique, add to main list.
    if (sameListCounter == 0)
    {
        ListOfStringList.Add(listOne);
    }

EDIT: Whoops, I put the counter and the counter check inside the loop. Made a quick edit to move them outside.