Two flags on the same pole is wrong, wrong, wrong. When in doubt, check the Boy Scout Handbook.
I'm in doubt because I can't find my old Handbook, but I can hardly imagine that it differs from The Flag Code itself:
f. When flags of States, cities, or localities, or pennants of societies are flown on the same halyard with the flag of the United States, the latter should always be at the peak.
BTW (to other posts), there are no exceptions for the Texas state flag.
It may be wrong, but it's done all the time. My local post office flies the U.S. flag with the MIA flag underneath.