修复来回切换红外遥控，导致信号文件重复出现在下拉列表中；

SATHelper/SATHelper/IRControlWnd.cpp

@@ -756,6 +756,7 @@ void CIRControlWnd::LoadSignals()
 	if (Global::g_Config.useTW)
 	{
 		filehelper fh;
+		m_vtsignal_tw.clear();
 		fh.getfiles_findout_subfolder(Global::g_Config.twSignaldir.c_str(), NULL, &m_vtsignal_tw);
 
 		m_wndSignalCombo.ResetContent();
@@ -767,6 +768,8 @@ void CIRControlWnd::LoadSignals()
 	else
 	{
 		filehelper fh;
+		m_vtsignal_gen.clear();
+		m_vtsignal_pro.clear();
 		fh.getfiles_findout_subfolder((Global::g_Config.signaldir + "\\general\\").c_str(), NULL, &m_vtsignal_gen);
 		fh.getfiles_findout_subfolder((Global::g_Config.signaldir + "\\product\\").c_str(), NULL, &m_vtsignal_pro);