The trio are approaching the end of their first season at Welford Road and have signed deals to extend their stay with the defending Guinness Premiership champions.
Argentina international Amorosino etched his name into Tigers history shortly after his arrival with the only try of the 22-17 win over South Africa and has scored four times in nine appearances this season.
Staunton, signed after gaining Premiership experience with Harlequins, Wasps and London Irish, has scored 156 points for Tigers and was the first player in the Guinness Premiership to reach 100 points this term.
Duffey, signed from East Midlands neighbours Nottingham last summer, made his debut in the home win over Worcester Warriors in October and has also made his first appearance in Heineken Cup rugby this season.
“I’m delighted all three have signed new contracts with us,” said Tigers head coach Richard Cockerill.
“Lucas came to us just before the start of the season and has shown some great natural talent while also getting used to the professional club game here. He is a very exciting player and we look forward to seeing him develop.
“Staunts has done an excellent job for us. He played a lot of rugby at the start of the season when we were without two other international fly-halves due to injury, and he settled in very quickly in a key position and he has made a big contribution.
“Joe has had to be patient this season with two experienced international hookers in the squad, but he is learning all the time and he has earned a new contract. He will continue to develop as a player here.”
