Error in cTrader native MovingAverage indicator.

In an MultiThreaded environment we sometimes get the following error while  running the CheckSMA function

An item with the same key has already been added. 

at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)    
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)    
at cTrader.Automate.Small.V1.Indicator.SmallIndicatorWrapperProvider.GetNested(ISmallChartSource smallChartSource, Type clrIndicatorType, Dictionary`2 parameterValues, AlgoContext algoContext)  
at cTrader.Automate.Small.V1.Indicator.SmallIndicatorAccessor.GetInternal[TIndicator](ISmallChartSource chartSource, Object[] parameterValues)
at cTrader.Automate.Small.V1.Indicator.SmallIndicatorAccessor.SimpleMovingAverage(DataSeries source, Int32 periods)    
at cAlgo.TU_TV.CheckSMA(Int32 period) in c:\Users\Edward\Documents\cAlgo\Sources\Indicators\........ 

It could be an error on our part or at Spotware. But as MA is one of the most commonly used indicators it is of the utmost importance to get it straight.

private int CurrentSmaPeriod = -1;

private void CheckSMA(int period)
{
    if (period <= 0 || CurrentSmaPeriod == period) return;
    i_SMAt = Indicators.MovingAverage(Bars.MedianPrices, period, MovingAverageType.Simple);
    CurrentSmaPeriod = period;
}

Hope it gets solved!