Is it legal to use 2 authorized computers in different households?
This is covered under the USAGE RULES section of the iTunes Terms of Service, which reads, in part:


  USAGE RULES
  
  (i) You shall be authorized to use iTunes Products only for personal,
  noncommercial use.
  
  (ii) You shall be authorized to use iTunes Products on five
  iTunes-authorized devices at any time, except for Content Rentals (see
  below).
  
  (iii) You shall be able to store iTunes Products from up to five
  different Accounts at a time on compatible devices, provided that each
  iPhone may sync tone iTunes Products with only a single
  iTunes-authorized device at a time, and syncing an iPhone with a
  different iTunes-authorized device will cause tone iTunes Products
  stored on that iPhone to be erased.


While I'm not a lawyer and this is not legal advice, I do not see where it limits usage to one person, or declares that all these devices and authorized computers must be owned or operated by only one person.

I suggest you carefully read the entire legal agreement if you want to resolve this for yourself.