The IDE interface requires only one cable. All pins straight from 1 to 1, 2 to 2 and so on. The drives can be connected in any order. Only remember that one should be jumpered as Master and the other as Slave. If only one drive is used, jumper it as Single (if such a mode exists, or most common Master else).
Controller Drive 1 or 2 Drive 1 or 2 +--+ +--+ +--+ |::|===================|::|============|::| <-Pin 1 |::|===================|::|============|::| |::|===================|::|============|::| |::|===================|::|============|::| |::|===================|::|============|::| |::|===================|::|============|::| |::|===================|::|============|::| +--+ +--+ +--+
Controller | Drive 1 | Drive 2 | |
---|---|---|---|
Wire 1-40 | 1-40 | 1-40 | 1-40 |