multiple definition of 'PointList::EmptyList'

[damateem]

I trying to update my toolset to wxWidgets 2.9.4 (from 2.8.11) and MinGW
4.7.2.

I've compiled wxWidgets without issue, but when I build my application,
I get the error message on several object files during linking.

multiple definition of 'PointList::EmptyList'

An additional linker message tells me "first defined here" at the
following line

IMPLEMENT_APP(C3App);

Has anyone seen this? Any tips for resolving it?

Thanks,
David