According to an older post on the forum, it's better to use Ubuntu's native touch support and I will condense the information that fixed this issue:
Update or make sure you're using version
0.20.0 or above for
xf86-input-wacom driver package:
Install touchegg package:
sudo apt-get install touchegg
OFF wacom's own touch guesture support so ubuntu's touchegg can take guesture control:
xsetwacom set "Wacom Bamboo 16FG 4x5 Finger touch" Gesture off
You may need to replace the name above in quotes with the name of your finger pen device name which you can find doing
xsetwacom --list devices
Use the touchegg configuration tool or edit the touchegg configuration file to adjust timeouts as needed.
You should now have working multi-touch support.