Finding duplicates between two lists

[LAVA2]

Hi,

There are two list as followes:

A1 A2
2 6
5 4
7 8
6 2
5 4

In A3 and A4 i would like to have duplicates sorted as followes:

A3 A4
2 6
5 4

Because 2,6 and 5,4 have occured twice same way or either way.

Thanks