Check by some unique field and if list does not containt such item add it
if (DataReceivedCollectionTr.FirstOrDefault(i => i.SymbolNameTr == SymbolNameTra) == null)
{
DataReceivedCollectionTr.Add(new DataTr() { SymbolNameTr = SymbolNameTra, TypeTr = TypeTra, AmountTr = AmountTra, ProfitLossTr = ProfitLossTra,PosID = PosID });
}