Your question translated using google translate .
Hi, since yesterday my contacts on icloud have inexplicably tripled. So each name is tripled in the mac and iphone address book. Usually logging off and logging in they would settle down but now I saw that the duplicates are right on icloud.com .... it would be a big problem to delete them one by one ...
If you have signed in with same Apple ID and password on the same network in Mac and iPhone or other apple devices the contacts on each device will get synced , if the same contacts are in devices they will be seen as duplicates ( as if you had already created contacts in Mac and the same are in iPhone ) .
To avoid it , disconnect the desired device by just signing out from Apple ID account , then delete the duplicate contacts in each device .
See the article If you see duplicate contacts after setting up iCloud Contacts - Apple Support