急.TServerSocket的onClientRead为什么会执行两次呢

在delphi2010中procedure TForm1.ServerSocketClientRead(Sender: TObject;
  Socket: TCustomWinSocket);
  var
  len:Word;
  buf:array of char;
  Data:string;
begin
   Socket.ReceiveBuf(len,2); //存放内容长度
   SetLength(buf,len);   //len是按字符数
   Socket.ReceiveBuf(Buf[0],len*2);  //len按字节数
   setLength(Data,len);
   move(buf[0],Data[1],len*2);
   InfoInit(Data);
end;