Preheat oven to 350 degrees F (175 degrees C).
In a large bowl, cream together shortening, margarine, brown sugar, white sugar, and peanut butter until smooth. Beat in the eggs one at a time until well blended. Combine the flour, baking soda, and salt; stir into the creamed mixture. Mix in the oats until just combined. Drop by teaspoonfuls onto ungreased cookie sheets.
Bake for 10 to 15 minutes in the preheated oven, or until just light brown. Don''t over-bake. Cool and store in an airtight container.