Ok I got it working… Here’s how:
Navigate to /opt/retropie/configs/mame-libretro
then edit emulators.cfg
change the default emulator to the 2010 version – here’s what it looks like below
lr-mame2003=”/opt/retropie/emulators/retroarch/bin/retroarch -L /opt/retropie/libretrocores/lr-mame2003/mame2003_libretro.so –config /opt/retropie/configs/mame-libretro/retroarch.cfg %ROM%”
default=”lr-mame2010″
lr-mame2010=”/opt/retropie/emulators/retroarch/bin/retroarch -L /opt/retropie/libretrocores/lr-mame2010/mame2010_libretro.so –config /opt/retropie/configs/mame-libretro/retroarch.cfg %ROM%”