WHOIS-contacts are details about domain name's contact persons for administrative and technical issues, which are shown in WHOIS-service's answers to requests about the domain name.
This information is open for unlimited number of persons.
RU-CENTER uses for notifications the e-mail addresses specified in the agreement (in the "e-mail" and "mnt-nfy" field), but not the e-mail addresses specified in the WHOIS-contacts' information.