Slightly soften one of the sherbets. Evenly pack the sherbet onto the bottom and the sides of a 4-cup metal mixing bowl, creating a 1/3-inch-thick layer. Freeze for 1 hour. Soften the second sherbet and spread it against the frozen sherbet, creating an inner layer. Freeze again for about an hour. Fill the center with the vanilla ice cream and refreeze, covering the surface with plastic wrap. Can be made up to a week in advance.
To serve, loosen the edges of the mold with a knife. Dip the mold very briefly in hot water, then invert onto a serving plate. Cut into wedges. Garnish with raspberries and mint.