Just want to see the icloud agenda, and not 2 agenda's

On my Iphone I just put a mark to show me the agenda from Icloud; every once in a while though it shows me both my agenda from my Mac, and the Icloud agenda, so I see the entries twice.

When I remove the mark from the Mac agenda again, after some time it will show me 2 agenda's again.

Does anyone knows how to get rid of this?