Post the zipped project file (*.cbp). Most likely you have wrong compiler/linker settings.
Hmm... I just booted it up today after getting home from work, and it compiled fine. I'm not sure exactly what happened, or how it resolved itself. I
do know that last night it compiled fine until I renamed a few files, afterwhich the linker started giving weird multiple definition errors, pointing to the same line for the 'first' and the 'multiple' definitions. And the log indicating that it was trying to link the offending file twice. And after fooling with it for entirely too long, I gave up hope.
I can still post the CBP file if you want to take a look at it, but methinks you'd be fixing a phantom issue.