var fileStream1 = new FileStream(@"File.ext", FileMode.Open, FileAccess.Read);
var fileStream2 = new FileStream(@"File.ext", FileMode.Open, FileAccess.Read);

var fileStream1 = new FileStream(@"File.ext", FileMode.Open, FileAccess.Write);
var fileStream2 = new FileStream(@"File.ext", FileMode.Open, FileAccess.Read);