Two computers with different libraries in the iCloud Photos.

I'm thinking about switching to iCloud Photos. However I have one iMac and one MacBook Pro. And the pictures in the MacBook Pro (in iPhoto) and the pictures in the iMac (Aperture Library) are maybe 30-40% different pictures (70-60% are the same pictures thanks to Photo Stream).

I was wondering if I enable iCloud Photos on both the computers, will those libraries merge? Is there a chance that I can lose pictures? (Or have duplicates?)

Did anybody do this? What was your experience?

Thanks!