The 26-year-old was the 18th of 19 new arrivals at Mazuma Stadium last summer.
However, he has now joined National League title favorites Stockport County on a deal until the end of the season.
Duffus had joined the Shrimps from National League side Bromley, having agreed a two-year deal at Mazuma Stadium.
A former Republic of Ireland Under-21 international, Duffus’ career also included spells at Everton, Bury, Oldham Athletic, Waterford and Yeovil Town, before joining Bromley.
He made his Morecambe debut in August’s defeat at Gillingham, the first of three appearances in a week.
However, after the third of them – Sheffield’s 1-0 defeat on Wednesday – it was revealed he had picked up a thigh injury which kept him out for several weeks.
He didn’t reappear until the 2-2 draw with Charlton Athletic in November with his last outing coming in the 2-0 loss at Rotherham United in February.
In all, he has played eight times for the club but is yet to score a goal.
County director of football Simon Wulson told his club’s website: “Courtney is an athletic striker who has a strong National League pedigree from his time at Yeovil and Bromley.
“He will add great competition and depth to the team as we now approach the final break-in.”
