When both ImageMagick and GraphicsMagick are installed, koffice-kde3 fails to build due to the configure script has detected both libraries installed on the system.  When it starts building it will fail with:

then mv -f ".deps/karbon.la.Tpo" ".deps/karbon.la.Po"; else
 rm -f ".deps/karbon.la.Tpo"; exit 1; fi
 /bin/sh /usr/local/bin/libtool --silent --tag=CXX --mode=link
 c++  -Wno-long-long -Wundef -Wall -W -Wpointer-arith -DNDEBUG -DNO_DEBUG -O2 -O2 -fno-strict-aliasing -pipe -Wno-non-virtual-dtor -fno-exceptions -fno-check-new -fno-common -DQT_CLEAN_NAMESPACE -DQT_NO_ASCII_CAST -DQT_NO_STL -DQT_NO_COMPAT -DQT_NO_TRANSLATION -DHAVE_KNEWSTUFF   -L/usr/local/lib -o
 karbon -R /usr/local/lib -R /usr/local/lib -R /usr/local/lib -R /usr/local/lib -R /usr/local/lib -no-undefined -L/usr/local/lib   -D_THREAD_SAFE -pthread  -L/usr/local/lib
 karbon.la.o
 libkdeinit_karbon.la -Wl,-export-dynamic -L/usr/local/lib -ljpeg  -L/usr/local/lib
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawSetViewbox'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawScale'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `DrawSetTextUnderColor'
 /usr/local/lib/libMagickCore.so: undefined reference to `DestroyMagickWand'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `DrawSetStrokeDashArray'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawSetStrokeWidth'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawColor'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawPathStart'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `DrawSetStrokeAntialias'
 /usr/local/lib/libMagickCore.so: undefined reference to `PopDrawingWand'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawAnnotation'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawSetStrokeLineCap'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `DrawPathEllipticArcAbsolute'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `DrawSetStrokeLineJoin'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawPathClose'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawPushClipPath'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `DrawSetStrokePatternURL'
 /usr/local/lib/libMagickCore.so: undefined reference to `PixelSetBlueQuantum'
 /usr/local/lib/libMagickCore.so: undefined reference to `NewPixelWand'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawComment'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `DrawSetFillPatternURL'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawComposite'
 /usr/local/lib/libMagickCore.so: undefined reference to `PixelSetRedQuantum'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawPushPattern'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawPopDefs'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `NewMagickWandFromImage'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawEllipse'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawAllocateWand'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `DrawPathLineToAbsolute'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawSetClipPath'
 /usr/local/lib/libMagickCore.so: undefined reference to `PushDrawingWand'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawPopClipPath'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawRender'
 /usr/local/lib/libMagickCore.so: undefined reference to `PixelSetQuantumColor'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `DrawPathMoveToAbsolute'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawSetStrokeColor'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawRotate'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawPopPattern'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawArc'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawRoundRectangle'
 /usr/local/lib/libMagickCore.so: undefined reference to
 `PixelSetOpacityQuantum'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawTranslate'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawLine'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawSetFillColor'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawSetFontSize'
 /usr/local/lib/libMagickCore.so: undefined reference to `PixelSetGreenQuantum'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawSetFont'
 /usr/local/lib/libMagickCore.so: undefined reference to `DestroyPixelWand'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawSetClipRule'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawRectangle'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawPushDefs'
 /usr/local/lib/libMagickCore.so: undefined reference to `PixelSetColor'
 /usr/local/lib/libMagickCore.so: undefined reference to `DrawPathFinish'
 gmake[3]: *** [karbon] Error 1
 gmake[3]: Leaving directory
 `/usr/ports/editors/koffice-kde3/work/koffice-1.6.3/karbon'
 gmake[2]: *** [all-recursive] Error 1
 gmake[2]: Leaving directory
 `/usr/ports/editors/koffice-kde3/work/koffice-1.6.3/karbon'
 gmake[1]: *** [all-recursive] Error 1
 gmake[1]: Leaving directory
 `/usr/ports/editors/koffice-kde3/work/koffice-1.6.3'
 gmake: *** [all] Error 2
 *** Error code 2

Fix: One solution proposed on the ports mailing list was to uninstall the ImageMagick port, rebuild editors/koffice-kde3 and then reinstall ImageMagick, while this works it is unacceptable to have to uninstall a port to get another port to build.

The correct solution is to patch the source configure script to skip the detection of ImageMagick when GraphicsMagick is installed.  see attached patch:

Patch attached with submission follows:
How-To-Repeat: cd /usr/ports/graphics/GraphicsMagick
make install
cd ../ImageMagick
make install
cd /usr/ports/editors/koffice-kde3
make build

The build will fail as shown above.