It's not a common problem, but I have encountered a situation occasionally where both headlights will burn out the same filament at once- - - -no light on low beam, for instance, and normal operation on high, or vice versa. Always check the voltage beginning right at the light connector plug, and trace the circuit backwards until you find the voltage loss.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!