If you are running high wattage this is common. On my 2000 4Runner they blew on the same day more than once-- the high wattage have low hours. Try the HIR bulbs--I have had mine for a year now running on many washboard roads here in Mexico and they are still going strong.
The bulbs are stock OEM. Does HIR-4 sound right? I'll pull one tomorrow to see. They cost A$20 from my local Toyota parts guy, which is painful but not bearly as painful as changing them. Unlike the LX 450 the bulbs are held into the back of the lamp by a flange which is snugged up by a nsaty sharp little lockring/circlip kind of thing. Bruised fingers every time
I'll start looking at alternators too
Hey, it's sunny and about 85 these days! I shouldn't whine!
Bit of bad luck hey. Youre luck you don't have sealed beams like mine they cost heaps to replace. High and low combo should be H4. Try supercheap might save a few dollars. Youre spot on about the weather nice to come home from work grab a stubby and relax in the pool
Strange that they should go in 6 months, but not strange that they blow closely in timing. They're designed to last X hours and vary in how long they last a little, so when one goes, the other isn't far behind.
Walking Eagle is spot on - unless you're a "night person" the bulbs were probably part of a poor batch, as they should give at least a couple years of service. The low beams usually go first, as they are usually in service longer. Look on the positive side - if you didn't have bad luck with that set of bulbs, you wouldn't have had any luck at all.