Yes you can
In Plus! Preferences, go to
Notifications and click on
Popup Defaults on the right. Uncheck the
Contact changes his/her name checkbox. Note: This will turn off
default notification for all your contacts. You may still have to furthermore disable per-contact setting by: Right-click on a contact in your contact list, select
Messenger Plus! Extras -> Notifications and uncheck
Contact changes his/her name 