There are at least two artists with this name:

1)
’60s-sounding Welsh blues singer Aimee Anne Duffy - known professionally as Duffy - released her debut single Rockferry in December 2007. After relocating to London in 2006, she came to the attention of Rough Trade. She is often compared to late ’60s soul diva Dusty Springfield and has experienced significant mainstream success with the single Mercy reaching #1 in the United Kingdom. The debut album, Rockferry, was released in March 2008, and also made #1 on the UK album chart. Bernard Butler of Suede worked extensively on the album, lending it an authentic and wonderfully produced lush ’60s sound.

The 24-year-old’s debut album, Rockferry, triumphed at the 2009 BRIT Awards for British Album, British Female Solo Artist, and British Breakthrough Act.

Official website of (Aimee Anne) Duffy: http://www.iamduffy.com/

2)
Duffy was a british band formed in London by Stuart Reffold, Barry Coote, Joe Nanson, Patrick Sarient and Will Wright. They played hard rock with strong progressive rock influences, similar to the early albums of Uriah Heep, Deep Purple and Humble Pie - with some influences of Jethro Tull as well.
https://www.discogs.com/artist/911568-Duffy-6