Add the dark and white rum, blood orange juice, orgeat, lemon juice and salt to a large pitcher, stirring to combine. Pour over ice-filled rocks glasses and garnish each glass with a lemon peel.
To serve: Add dry ice pellets to a large, shallow platter. Put the glasses on the platter, surrounding each glass with the dry ice but being careful not to touch the pellets with your hands. Carefully serve the drinks on the platter.