The Mach HID is bi-xenon. When the "brights" are selected the mechanical cutoff shield is physically moved out of the way, allowing a full circle of illumination. At the same time, the high beam halogen lights, the inboard ones, should also come on. There is something wrong with the wiring if they don't. That said, the halogen really don't so very much in addition to the high-beam HID.
Use this link to figure out what's going on with the wiring:
Mine: 2002 Focus SVT: 142k, Sonic Blue, #1654, All Options
Mods: Tom's Tune, Borla, HFC, STS, Painted Machs, Euro Grill, FRPP Springs
Hers: 2010 Focus SES: 67k, Ebony, Auto, Moon and Tune