Managing duplicate contacts

Hi

I have always assumed that I should set Contacts to display entries 'on my mac', and use this as the 'master', after all you are not always in a wifi area when you want to input fresh data, and I have assumed that iCloud syncs automatically when one is with wi fi reach, and duly updates any other devices like iphone or ipad. Am I right ?

However, when i set Contacts to display entries 'on my mac' it displays duplicate and even triplicate entries which is irritating to say the least. Surely if I go to prefs and turn off the cloud account it wont update and I don't want that, I want cloud to keep up to date. So what is the best way to use Contacts that gives a single updated list without duplicates ???

In addition, I want to import from my outlook work station, I have followed guides before but the data gets lost somewhere, and given that was two years ago perhaps things are a bit more windows friendly than they were then, has anyone done this sucesfully and can give me a lead?

thanks and regards