Another note: You can set time length as additional criteria. To allow some inaccuracy in cuts at ends, set limit to 95 to 98% (depends on material). Setting this parameter also reduces compare time substantially, since files with unequal times (not the same as size) are disregarded and not compared by further algorithms. This circumvents also the problem of files which are similar at the first minute. Another advantage ist that typically different recordings (normal, instrumental, live) of the same song differ enough in time and thus are sorted out beforehand.
