It’s not a repetition because in the classical onion and tomato salad the onion plays the major role and tomato is just a play-fellow.
These are variants that include tomato, onion, oil, salt, vinegar and wild marjoram; but according to local habits it is possible to add also all the following ingredients or just a part of them: spicy green peperoncino, anchovy fillets, cucumbers, peppers, green olives, basil, black olives, portulaca, rapanello and even also boiled potatoes.
