Stir lemon gelatin, lime gelatin, and 2 cups boiling water in a bowl until gelatin has thoroughly dissolved. Mix 2 cups cold water into gelatin and pour into 8 1-cup miniature glass trifle dishes, filling dishes halfway. Refrigerate until partially set, about 30 minutes; arrange 2 or 3 slices of banana on top of the gelatin. Return to refrigerator.
Mix strawberry gelatin with 2 cups boiling water in a bowl until gelatin is thoroughly dissolved; stir 2 cups cold water into strawberry gelatin. Refrigerate until cooled and beginning to set, about 15 minutes. Spoon about 1/2 cup strawberry gelatin gently on top of each serving; top with 4 or 5 sour cherries and two strawberry halves, cut sides facing up. Return to refrigerator and chill until firm, about 4 hours.