Cream 1/4 cup shortening in a medium mixing bowl; gradually add 1/4 cup brown sugar, beating until light and fluffy. Add 1 egg, beating well. Stir in melted butterscotch morsels and 1/2 teaspoon vanilla.
Sift together 1 cup flour, soda, and 1/2 teaspoon salt in a small mixing bowl; add to creamed mixture, stirring until well blended.
Roll to a 10- x 7-inch rectangle between two sheets of waxed paper; set aside.
Repeat mixing and rolling procedure with remaining ingredients, substituting 1/2 cup granulated sugar for brown sugar, baking powder for soda, and chocolate for butterscotch.
Remove waxed paper from tops of dough, and invert chocolate rectangle directly on top of butterscotch rectangle. Remove remaining waxed paper. Roll up jellyroll fashion, beginning with long side; wrap in waxed paper. Chill at least 1 hour.
Cut into 1/4-inch slices. Place 2 inches apart on lightly greased cookie sheets. Bake at 375° for 6 minutes or until lightly browned. Remove from cookie sheets, and cool on wire racks.