says "Whats this some sort of marital aid?
Contrary to popular belief, Double Donkey Kong is not a marital aid. It is an upgrade kit for Donkey Kong Junior arcade games that adds several capabilities that the original game did not have, and allows you to play the original Donkey Kong as well.
says "So, if it doesn't vibrate, then what does it do?"
The Double Donkey Kong kit has six upgraded features from the original Donkey Kong Junior.
You can switch from Donkey Kong to Donkey Kong Junior instantly by pressing player one start and player two start at the same time.
Your high scores are now permanently saved for both titles. The original game reset the high scores every time it was turned off.
The original Donkey Kong series did not have a freeplay mode. This kit adds that feature.
The original did not allow you to select the option of attract mode sound. This kit adds that feature.
Extensive self test diagnostics have been added. This allows you to be instantly aware of any abnormalities with your valuable game boards.
All dip switches are now also available via a setup menu. So you don't have to open up the cabinet to change settings anymore.
says "I assume shipping will be discrete, plain brown envelope and all that?"
These upgrade kits are available from several online vendors. You simply send in your original Donkey Kong Junior boardset, and they upgrade it and send it back to you. http://www.mikesarcade.com does the upgrade for $160. Several other vendors also offer this product in completed form on eBay. Double Donkey Kong marquees, control panel overlays, and other related products are usually sold separately.
Please note that this kit only works on original Donkey Kong Junior boardsets. The Donkey Kong hardware was essentially a subset of the Donkey Kong Junior hardware, which allows that software to run on either type of board. Bootleg boardsets do not work with this upgrade. You should also be aware that the sound for Donkey Kong is just slightly different in pitch, but it is so close that most people would never notice.
Pac-Man/Puckman/Ms. Pac-Man owners may want to check out the Multi Pac, which is a similar upgrade for the Pac series of games. While Millipede owners may want to familiarize themselves with the Multipede kit. Tempest owners could do worse than installing the Tempest Multigame, and the Williams Multigame is a must have upgrade for owners of Joust or Robotron 2084 hardware.
You can also get the same combination of games for the NES with the Donkey Kong Classics cartridge.