Pet Person was the original incarnation of Little Computer People, before it was brought by Activision as a concept, and re-designed/developed by David Crane into the game we all know and love.
The original concept was fairly similar to the final game, but Activision would add the likes of a card game and make changes to sound and music throughout. According to Todd Marshall, a lot was changed overall from the original game.
The original concept was about a year in the making, suggesting that it was probably created and sold in 1984 to Activision.
It is possible that something of the original concept still exists, so its hoped that for posterity it could be found some day. For more details, check out this interview with Todd Marshall.
Contributions: Andrew Fisher, Brian Bagnall, Scott Stilphen