Looks like you put the definition of a variable in header files and not only the declaration. This leads to a duplicate definition for every .cpp file which includes a certain header name. See e.g. Splitting cpp files - #2 by maxgerhardt.
Looks like you put the definition of a variable in header files and not only the declaration. This leads to a duplicate definition for every .cpp file which includes a certain header name. See e.g. Splitting cpp files - #2 by maxgerhardt.