While I am glad you were able to successfully install Duokan Lite using your method described above, it isn't the way it should actually be done.
Duokan Lite should first be installed on a system that isn't Jailbroken. As such, to install it successfully the way it should be done, you should:
Code:
1. Uninstall all of the hacks you have installed (such as Launchpad) (not Jailbreak hack yet)
2. Uninstall the Jailbreak hack
3. Install Duokan Lite, using the latest version from their website, and copying the appropriate 'DK_System' and '.bin' file to your Kindle Keyboard's home directory. Then updating it.
4. Install Jailbreak hack
5. Install all of the other hacks you want (such as Launchpad)
6. Optional: change dual boot option to boot KindleOS as default OS after restart: append "DefaultSystem=3" to 'DK_System/Lite/config.ini'
7. Optional: adding Launchpad shortcuts to boot Duokan Lite within Kindle OS:
duokan_lite.ini
[Actions]
; Duokan Lite (launch from KindleOS)
D L = !source /mnt/us/launchpad/startdkl.sh
D M = !source /mnt/us/launchpad/startdkl2.sh
D N = !source /mnt/us/launchpad/startdkl3.sh
D X = !echo "send 102">/proc/keypad; source /mnt/us/launchpad/stopdkl.sh
D Z = !killall -9 KindleApp
And from then on, to update Duokan Lite, you can merely boot into it, and update it from its System Settings menu. No need to do anything else. You could copy over the latest 'DK_System' folder to your Kindle's home directory, overwriting what you have already, but I do not believe that is necessary. It is just another way.
Also, the original Duokan is quite old in comparison to Duokan Lite, so I do not really know what would be the advantage of having both on a Kindle 3/Keyboard. Duokan Lite was made specifically for it, and is updated regularly. So, for those who don't know much about this, I suggest just using Duokan Lite. Just my opinion.