List Symbols = new List
{
"EURUSD",
"AUDUSD",
"USDJPY",
"AUDJPY",
"EURCHF",
"EURGBP",
"EURJPY",
"GBPAUD",
"GBPJPY",
"NZDUSD",
"USDCAD",
"USDCHF",
"USDJPY",
};

List SymbolData = new List();

public override void Initialize()
{
SetCash(50000);
SetStartDate(2009, 1, 1);

foreach (var symbol in Symbols)
{
AddSecurity(SecurityType.Forex, symbol, Resolution.Minute);

First day of using C# so i am sure i have made a silly mistake

"Backtest Error: Error initializing algorithm: Algorithm.AddSecurity(): The key already existed in the dictionary."