released on August 22, 2018.
| DDU-DU DDU-DU [CD+DVD] Catalog: AVCY-58710 | 1. | DDU-DU DDU-DU (JP Version) | 3:29 | 2. | DDU-DU DDU-DU (뚜두뚜두) | 3:29 | 3. | Forever Young | 3:57 | 4. | Really | 3:17 | 5. | See U Later | 3:18 |
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| DDU-DU DDU-DU [CD] Catalog: AVCY-58711 | 1. | DDU-DU DDU-DU (JP Version) | 3:29 | 2. | DDU-DU DDU-DU (뚜두뚜두) | 3:29 | 3. | Forever Young | 3:57 | 4. | Really | 3:17 | 5. | See U Later | 3:18 |
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| DDU-DU DDU-DU [JENNIE Ver.] [CD] Catalog: AVCY-58712 | 1. | DDU-DU DDU-DU (JP Version) | 3:29 |
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| DDU-DU DDU-DU [JISOO Ver.] [CD] Catalog: AVCY-58714 | 1. | DDU-DU DDU-DU (JP Version) | 3:29 |
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| DDU-DU DDU-DU [LISA Ver.] [CD] Catalog: AVCY-58713 | 1. | DDU-DU DDU-DU (JP Version) | 3:29 |
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| DDU-DU DDU-DU [ROSE Ver.] [CD] Catalog: AVCY-58715 | 1. | DDU-DU DDU-DU (JP Version) | 3:29 |
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