You can put two IDE drives (master & slave) on one controller. You just need to have a 3 connection (2 drives, 1 MB) IDE cable and jumper the drives (one as master, other as slave). Also make sure the IDE Secondary/Slave isn't disabled in the BIOS, best set to AUTO.
I'm talkign about the ide controller in the bios, not the ide cable.
Yes a cable can have 2 devices on it, and maybe even the jumpers set right. But if the bios doesn't have a IDE slave drive controller (which is common in budget dell pc's), then it won't recognize the slave drive.