Multiple errors 'Multiple definition...' First defined here' .... when build

I have 3 custom dlls.
1.- dll_A
2.- dll_B it is a plugin with custom widgets that use classes of dll_A
3-. dll_C , use some classes of dll_A

The 3 dll's are built ok, without errors.

Ok, later I have tow approachs to run and build my prog.
I have for A,B,C

Code:

---

#if defined(###_LIBRARY)
#  define 1###SHARED_EXPORT Q_DECL_EXPORT
#else
    #if defined(###_DIRECT)
    #  define 1###SHARED_EXPORT        
    #else
    #  define 1###SHARED_EXPORT   Q_DECL_IMPORT
    #endif
#endif

---

Depending If I'm working with Library approach or direct way I define
DEFINE += ###_LIBRARY or DEFINE += ###_DIRECT ( in this case I use all the files as is they were loaded into my project)

All worked fine until I want to use the DLL_C. I have a lot of errors
'Multiple definition...' First defined here' ....

My program use classes of DLL_A and DLL_B, which use itself classes of DLL_A.

If I use the LIBRARY approach I have 5 errors against 395 errors if I use DIRECT approach. In any case, I have this 'multiple definition'... what can I do to solve it ?
Thanks

You can remove multiple definitions of symbols from your code. The compiler tells you where they are.