C / C++ / MFC

--------------------Configuration: HydroExe - Win32 Debug--------------------
Linking...
HydroExeDlg.obj : error LNK2005: "unsigned int  tid" (?tid@@3IA) already defined in HydroExe.obj
HydroExeDlg.obj : error LNK2005: "class CSerialComm  SerialComm" (?SerialComm@@3VCSerialComm@@A) already defined in HydroExe.obj
HydroExeDlg.obj : error LNK2005: "class CDecoder  Decoder" (?Decoder@@3VCDecoder@@A) already defined in HydroExe.obj
Debug/HydroExe.exe : fatal error LNK1169: one or more multiply defined symbols found
Error executing link.exe.

HydroExe.exe - 3 error(s), 1 warning(s)
------------------------------------------------------------------------------

int records::InsertNode(char m_last_name[], char m_first_name[], long m_ssan)
{
	ListNode *NewNode, *NodePtr, *PreviousNode;

	// Allocate a new node & store values
	NewNode = new ListNode;
	strcpy(NewNode->last_name, m_last_name);
	strcpy(NewNode->first_name, m_first_name);
	NewNode->ssan = m_ssan;
	
	// If there are no nodes in the list
	// make NewNode the first node
	if (!Head)
	{
		Head = NewNode;
		NewNode->Next = NULL;
	}
	else	// Otherwise, insert NewNode at end
	{
		// Initialize NodePtr to head of list
		NodePtr = Head;
		

		<font color="red">PreviousNode = NodePtr;</font>

		// Skip all nodes whose Value member is less
		// than m_ssan.

		while (NodePtr != NULL && NodePtr->ssan < m_ssan)
		{	
			PreviousNode = NodePtr;
			NodePtr = NodePtr->Next;
		}

		// Insert the node after the one pointed to
		// by PreviousNode and before the one pointed to
		// by NodePtr.
		PreviousNode->Next = NewNode;
		NewNode->Next = NodePtr;
	}
	return 0;
}