클래스로 이중 링크드 리스트를 만들어 보고 있습니다.

객체를 선언하면 슥슥슥 해서 나중에 편하게 사용하기 위해 작업중이지요.
근데 에러가 나는데, 무슨 에러인지 모르겠습니다.

에러의 내용은

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Compiling...
Main.cpp
Linking...
DoubleLinkedListControl.obj : error LNK2005: "void __cdecl clrscr(void)" (?clrscr@@YAXXZ) already defined in DoubleLinkedList.obj
DoubleLinkedListControl.obj : error LNK2005: "void __cdecl gotoxy(int,int)" (?gotoxy@@YAXHH@Z) already defined in DoubleLinkedList.obj
DoubleLinkedListControl.obj : error LNK2005: "int __cdecl wherex(void)" (?wherex@@YAHXZ) already defined in DoubleLinkedList.obj
DoubleLinkedListControl.obj : error LNK2005: "int __cdecl wherey(void)" (?wherey@@YAHXZ) already defined in DoubleLinkedList.obj
DoubleLinkedListControl.obj : error LNK2005: "void __cdecl setcursortype(enum CURSOR_TYPE)" (?setcursortype@@YAXW4CURSOR_TYPE@@@Z) already defined in DoubleLinkedList.obj
Main.obj : error LNK2005: "void __cdecl clrscr(void)" (?clrscr@@YAXXZ) already defined in DoubleLinkedList.obj
Main.obj : error LNK2005: "void __cdecl gotoxy(int,int)" (?gotoxy@@YAXHH@Z) already defined in DoubleLinkedList.obj
Main.obj : error LNK2005: "int __cdecl wherex(void)" (?wherex@@YAHXZ) already defined in DoubleLinkedList.obj
Main.obj : error LNK2005: "int __cdecl wherey(void)" (?wherey@@YAHXZ) already defined in DoubleLinkedList.obj
Main.obj : error LNK2005: "void __cdecl setcursortype(enum CURSOR_TYPE)" (?setcursortype@@YAXW4CURSOR_TYPE@@@Z) already defined in DoubleLinkedList.obj
Debug/CDoubleLinkedList.exe : fatal error LNK1169: one or more multiply defined symbols found
Error executing link.exe.
---------------------------------------------

이거 입니다. 뭘까요-_-; 생전 처음보는 에런데 말이죠. 흠;