When I purchase TV shows on my iPad 2, why are they automatically downloading on my Mac? I would prefer not to download these shows to my MacBook Air as 


it doesn't have enough free disk space and 
it leads to sync issues when I plug in my iPad.


They don't seem to recognize the shows as the same so I end up with duplicate copies of many episodes.

How can I configure iTunes to achieve this?
Perhaps you could try stopping iTunes from automatically checking for bought content to download. This way, if you buy something on your iPad you would have to manually download it on your Mac. This can be done by going to iTunes>Preferences..., then to the "Store" tab and unchecking "Always check for available files."

Hope it Helps!