Central defender Duffy is a former Welsh international having been capped 13 times for his country.
The 33-year-old started his career at Swansea City before moving on to Portsmouth but struggled to break into Pompey's first team on a regular basis and instead gained experience from loans at Burnley, Swansea and Coventry.
After half a campaign at Millwall, the defender settled at Exeter City, spending three seasons with the Grecians in League One.
He left St James Park to join Port Vale and helped the Valiants to win promotion from League Two during his first season in Staffordshire before establishing them as a League One outfit.
He dropped down two divisions to join Eastleigh in the National League but left without making an appearance and moved to Notts in June 2016.
Home kit: Available
Away kit: Available
Boots & socks: Bethany West