When I set the switch to turn on the low beam, both the low and high beams became lit. I think the dashboard also showed the high beam indicator. This problem was fixed by simply disconnecting the wiring, cleaning the terminals, and reinserting the terminals. This wiring was connected to the aftermarket HID ballast on a 2002 Acura RSX.
Obviously there were faulty connections at the terminals. How can you explain the behavior (both low and high being lit) that resulted from the faulty connections?