AAccentAigu.cs

using System;

class Program
{
    static void Main()
    {
        var á = 1;// U+0061 U+0301
        var á = 2; // U+00E1

        Console.WriteLine(á == á); // false

        var x = nameof(á);
        var y = nameof(á);

        Console.WriteLine(x == y); // false
        Console.WriteLine(string.Equals(x, y, StringComparison.CurrentCulture)); // true
    }
}

濁点.cs

using System;

class Program
{
    static void Main()
    {
        var が = 1; // U+304B U+3099
        var が = 2; // U+304C

        Console.WriteLine(が == が); // false

        var x = nameof(が);
        var y = nameof(が);

        Console.WriteLine(x == y); // false
        Console.WriteLine(string.Equals(x, y, StringComparison.CurrentCulture)); // true
    }
}