Card dealing blackjack problem

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C#

Hello, I am writing a blackjack program in C# using Windows Forms Apps, I have been able to create the deck, and shuffle, and deal out cards to make them appear in a listbox. The problem that I am having is the dealer deals the same two cards out to both the player and the dealer. I had it working before using two decks one for the dealer and one for the player, however sometimes I would get the same card. I need to figure out how to use one deck and get it to deal 4 cards. I believe that my problems are either in the foreach loops to display the cards, or in the Form 1 load, please take a look any help would be greatly appreciated:
Here's my code for the two parts I believe to be wrong:

public partial class Blackjack : Form
   {


       string[] card = new string[53];
       string[] playerHand = new string[10];
       string[] dealerHand = new string[10];

       public Blackjack()
       {
           InitializeComponent();
       }


       private void Blackjack_Load(object sender, EventArgs e)
       {

           int top = 1;
           CreateDeck(card);
           RandomizeDeck(card);
           RandomizeDeck(card);



           string[] player = new string[10];
           string[] dealer = new string[10];
           for (int i = 0; i < 10; i++)
               dealer[i] = "";

           GetCard(dealer, card, ref top);     //// this is where I believe
           GetCard(dealer, card, ref top);     //// part of the problem is
           while (HValue(dealer) < 17)
               GetCard(dealer, card, ref top);
           GetCard(player, card, ref top);
           GetCard(player, card, ref top);

       }
      //// I believe the main problem is here with the two foreach loops

      //// Is there a better way to display the cards in the listboxes?

       private void btnStart_Click(object sender, EventArgs e)
       {
           {
               int countPlayer = 0;
               int countDealer = 0;

               foreach (string a in card)
               {

                   if (a != null)
                   {
                       string b = a;
                       for (int i = 0; i < playerHand.Length; i++)
                       {
                           if (playerHand[i] == null)
                           {
                               playerHand[i] = b;
                               break;
                           }
                           if (countPlayer == 2)
                           break;
                           this.lstYou.Items.Add(b);
                           countPlayer++;
                       }


                   }
               }
               foreach (string a in card)   /// this is where i believe
               {                            /// my problem is
                   if (a != null)
                   {
                       string b = a;
                       for (int i = 0; i < dealerHand.Length; i++)
                       {
                           if (dealerHand[i] == null)
                           {
                               dealerHand[i] = b;
                               break;
                           }
                           if (countDealer == 2)
                               break;
                           this.lstDeal.Items.Add(b);
                           countDealer++;


                       }
                   }
               }
           }

       }
 }
       }