Many compared the plots of...
The Raid (2011) vs Dredd (2012)
...and accused Dredd of copying The Raid. Forgetting that Dredd was written and shot before The Raid. Both are awesome.
The Godfather (1972) vs Once Upon A Time In America (1984)
Same story really. Leone had his movie in pre-production/scripting way before Coppola was hired. Again both are awesome.
The Full Monty (1997) vs Brassed Off (1996)
Both films about working class men finding a way out of the scrapheaps that Thatcher chucked their generation/industiries/communities onto. Full Monty was a collosal boxoffice hit, while Brassed Off did poorly but is infinitely superior IMO.
The late Pete Postlethwaite's best performance IMO...