require "digest/md5"

a = Dir["*"].group_by {|f|
    File.size(f)
}.select {|k,v| v.size > 1 }.values

b=a.map{|arr|
 arr.group_by {|v1|
  Digest::MD5.hexdigest(File.read(v1))
 }.select {|h,f| f.size > 1 }.values
}.map {|x|x[0]}.compact


c= b.map {|x|x.sort_by{|y| File.mtime(y)}[0..-2]}.flatten

File.delete(*c)