Multiple async requests on non-public API throws invalid api key exception

[rfcdejong]

This works

var ordersTask = _poloniexClient.Markets.GetOpenOrdersAsync(ethCurrencyPair, 10);
var orders = ordersTask.Result;
var myOrdersTask = _poloniexClient.Trading.GetOpenOrdersAsync(ethCurrencyPair);
var myOrders = myOrdersTask.Result;
var myTradesTask = _poloniexClient.Trading.GetTradesAsync(ethCurrencyPair, DateTime.Now.AddHours(-4), DateTime.Now);
var myTrades = myTradesTask.Result;

This throws an exception about invalid api key

var ordersTask = _poloniexClient.Markets.GetOpenOrdersAsync(ethCurrencyPair, 10);
var myOrdersTask = _poloniexClient.Trading.GetOpenOrdersAsync(ethCurrencyPair);
var myTradesTask = _poloniexClient.Trading.GetTradesAsync(ethCurrencyPair, DateTime.Now.AddHours(-4), DateTime.Now);

Task.WaitAll(ordersTask, myOrdersTask, myTradesTask)

var orders = ordersTask.Result;
var myOrders = myOrdersTask.Result;
var myTrades = myTradesTask.Result;