| Official |
|---|
| 1.8 | 佐之助&恵 duet 「2 Of A Kind!」 | 4:08 | 上田祐司&土井美加 | るろうに剣心 -明治剣客浪漫譚- ソングス | Various Artists | Album | | Sony Records | SRCL-3620 |
| 2.5 | 2 Of A Kind! | 4:05 | 相楽左之助(上田祐司)&高荷恵(土井美加) | るろうに剣心 -明治剣客浪漫譚- 〜Brilliant Collection〜 | Various Artists | Album + Compilation + Soundtrack | | SPE Visual Works Inc. | SVWC-1002, SVWC-1003, SVWC-1004 |
| 2.6 | 2 Of A Kind! | 4:04 | 上田祐司 & 土井美加 | アニメーション 「るろうに剣心-明治剣客浪漫譚-」 COMPLETE CD-BOX | Various Artists | Album + Compilation + Soundtrack | | SME Visual Works Inc. | SVWC-1011, SVWC-1012, SVWC-1013, SVWC-1014, SVWC-1015, SVWC-1016, SVWC-1017, SVWC-1018, SVWC-1019, SVWC-1020, SVWC-1021, SVWC-1022 |
| Bootleg |
|---|
| 2.5 | 2 Of A Kind! | 4:05 | 朝倉紀行 | るろうに剣心 -明治剣客浪漫譚- | 朝倉紀行 | Album + Compilation + Soundtrack | | 笙美 | GGG-121, GGG-122, GGG-123 |
| 2.6 | 2 of a Kind! | 4:04 | 上田祐司 & 土井美加 | Rurouni Kenshin Complete CD-BOX | Various Artists | Album + Compilation + Soundtrack | | MIYA RECORDS | MICA-0103, MICA-0104, MICA-0105, MICA-0106, MICA-0107, MICA-0108, MICA-0109, MICA-0110, MICA-0111, MICA-0112, MICA-0113, MICA-0114 |
| Pseudo-Release |
|---|
| 2.6 | 2 of a Kind! | 4:04 | Yūji Ueda & Mika Doi | Rurouni Kenshin Complete CD-BOX | Various Artists | Album + Compilation + Soundtrack | | | |
| 1.8 | Sanosuke & Megumi duet ~2 Of A Kind!~ | 4:08 | 上田祐司 & 土井美加 | Rurouni Kenshin Songs | Various Artists | Album | | | |
| 2.5 | 2 of a Kind! (Megumi and Sanosuke) | 4:05 | 朝倉紀行 | Rurouni Kenshin: Brilliant Collection | 朝倉紀行 | Album + Compilation + Soundtrack | | | |