hash="SHA256";
minSize=Quantity[1,"Megabytes"];
allfiles=Once@Select[FileNames["*","",∞],!Once@DirectoryQ[#]&&Once@FileSize[#]>minSize&];
data={#,Once[FileHash[#,hash,All,"HexString"]]}&/@allfiles[[;;5]];
Grid[Select[GatherBy[data,Last],Length[#]>1&][[All,All,1]]]