Thank you for your recommendation. The application saved me a lot of time. Unfortunately it solved the effect not the cause. However, I found a solution ... after restoring the contacts I deleted the contacts on the Google account and stopped the synchronization for "Contacts". I think the problem is with the google contacts synchronization application and not the ROM.This application will fix your problems. I used to have this situation on another phone after changing rom.
https://play.google.com/store/apps/details?id=com.compelson.optimizer&hl=en
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Unfortunately, after one day of operation the contacts were doubled, tripled again. It seems that this bug is not related to syncing with the google account that was stopped.
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