uploaded mac and iphone libraries, now have duplicate photos on iphone

I have a MacBook Air, late 2013 model running Yosemite 10.10.3, and an iPhone 6 running iOS 8.3. I have previously imported my iPhone 6's photos into iPhoto. When I downloaded 'Photos', I also signed up for an iCloud account, and purchased storage.

Long story short, I have uploaded all of my iPhone 6's photos to my iCloud photo library, and my MacBook is around 50% finished uploading, I have noticed that some of my photos have duplicated on my phone. I have the setting 'Optimize iPhone storage' and 'Optimize Mac storage'.

I'm wondering if this is because I had a copy of them on both my phone and my MacBook.

Any help or advice would be appreciated.