find equal element rows in a matrix

I have a matrix, in witch some rows have the same elements in different order. I want to keep only one row that has a specific set of elements. for example, if I have:

      1  3
      2  5 
      3  1
      2  3
      5  2

I would like to convert this matrix to:

1  3
2  5
2  3

anyone?

[Terence Etchells]

which

Answer 1

[Adam]

unique( sort( a, 2 ), 'rows' )

assuming a is your input array