Ok I don't know the context of the error (I linked to the code, so that may help). It doesn't tell me where the error is taking place (because it's not specific to one of the lines. Here is the error:
cd "/Users/atg/Desktop/Projects/Programming Project/Builds/Basic_SDLOGL_001"
/usr/bin/g++-4.0 -o /Users/atg/Desktop/Projects/Xcode\ Projects/Deployment/Basic_SDLOGL_001.app/Contents/MacOS/Basic_SDLOGL_001 -L/Users/atg/Desktop/Projects/Xcode\ Projects/Deployment -F/Users/atg/Desktop/Projects/Xcode\ Projects/Deployment -F/Library/Frameworks -filelist /Users/atg/Desktop/Projects/Xcode\ Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001\ (Upgraded).build/Objects-normal/ppc/Basic_SDLOGL_001.LinkFileList -framework GLUT -framework Foundation -framework AppKit -framework OpenGL -framework Cocoa -arch ppc -Wl,-Y,1455 -framework SDL
/usr/bin/ld: multiple definitions of symbol _curr_piece
/Users/atg/Desktop/Projects/Xcode Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001 (Upgraded).build/Objects-normal/ppc/sdl_tetris_002.o definition of _curr_piece in section (__DATA,__common)
/Users/atg/Desktop/Projects/Xcode Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001 (Upgraded).build/Objects-normal/ppc/Other_functions.o definition of _curr_piece in section (__DATA,__common)
/usr/bin/ld: multiple definitions of symbol _fileout
/Users/atg/Desktop/Projects/Xcode Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001 (Upgraded).build/Objects-normal/ppc/sdl_tetris_002.o definition of _fileout in section (__DATA,__common)
/Users/atg/Desktop/Projects/Xcode Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001 (Upgraded).build/Objects-normal/ppc/Other_functions.o definition of _fileout in section (__DATA,__common)
/usr/bin/ld: multiple definitions of symbol _next_piece
/Users/atg/Desktop/Projects/Xcode Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001 (Upgraded).build/Objects-normal/ppc/sdl_tetris_002.o definition of _next_piece in section (__DATA,__common)
/Users/atg/Desktop/Projects/Xcode Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001 (Upgraded).build/Objects-normal/ppc/Other_functions.o definition of _next_piece in section (__DATA,__common)
/Users/atg/Desktop/Projects/Xcode Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001 (Upgraded).build/Objects-normal/ppc/tile_init_001.o definition of _curr_piece in section (__DATA,__common)
/Users/atg/Desktop/Projects/Xcode Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001 (Upgraded).build/Objects-normal/ppc/tile_init_001.o definition of _fileout in section (__DATA,__common)
/Users/atg/Desktop/Projects/Xcode Projects/Basic_SDLOGL_001.build/Deployment/Basic_SDLOGL_001 (Upgraded).build/Objects-normal/ppc/tile_init_001.o definition of _next_piece in section (__DATA,__common)
collect2: ld returned 1 exit status
Ok I see what you mean now. I don't know how it can say that though, because I checked on some of these things, and I didn't define any of these symbols in tile_init_001.cpp like it says I did. So what does it mean?