linker error: Previous Definition Different : _GL_VERTEX_ARRAY_EXT

[Cris]

.objs\Release\src\base\glee\glee_h.obj(glee_h)  Offset 0C27AH Record 
Type 0091
  Error 1: Previous Definition Different : _GL_VERTEX_ARRAY_EXT

What can cause this linker error?

Previously I had all files in /src and I moved them in /src/base (with 
the already existing subdirectories).
I had to add base. to all imports.
Original:
import glee.glee;
import glee.glee_h;

Now:

import base.glee.glee;
import base.glee.glee_h;

etc.

The program compiles but cannot link and multiple errors like the quoted 
  one are issued when linking.

As I see they are all about constants.

Cris