Two images appear each time I import pics into iPhoto

Are you using iOS 8.1 on your iPhone? And not shooting HRD with the option "Keep normal photo" enabled? Then you might be suffering from a bug, that happens in iPhoto and Aperture:

Try, if disconnecting and plugging in again will help. For some users with an iPhone 5s it helped to unplug the iPhone, when iPhoto has been showing duplicates, and then to plug it in again. And then the duplicates vanished. Give it a try.

Apple is investigating this problem.

Re: Aperture Imports Duplicates and Triplicates of Photos from my iPhone 6 Plus

But there is no definitive fix yet: iPhoto imports 2 of every photo - iPhone 6

I experienced what you are just once. I tried the unplugging method that léoine mentioned and that got rid of the duplicates and let me import only one copy of each photo. Not a fix but a possible workaround.

Surprising enough I've not experienced that again.