In Harry Potter and the Half Blood Prince when Harry and Dumbledore are in Slughorn's memory they see see Tom Riddle with a bunch of other students in Slughorn's office. Among them are Lestrange and Avery:
'Good gracious, is it that time already? You'd better get going, boys, or we'll all be in trouble. Lestrange, I want your essay by tomorrow or it's detention. Same goes for you, Avery.'
Harry Potter and the Half Blood Prince Pg 463
In Harry Potter and the Deathly Hallows when Harry is in Snape's Memory he sees a conversation between Lily and Snape where Lily mentions an Avery:
'...thought we were supposed to be friends?' Snape was saying. 'Best friends?'
'We are, Sev, but I don't like some of the people you're hanging around with! I'm sorry, but I detest Avery and Mulciber!...'
Harry Potter and the Deathly Hallows Pg 540
Tom Riddle and Severus Snape are not in Hogwarts at the same time so my guess is that the second Avery is a son or some relative of the first. Is that right?