array_cat without duplicity

Hi!

Postgresql: version 8.1.11

Is there a way to concatenate two arrays without duplicity?

This select return duplicity:

SELECT array_cat(ARRAY[1,2], ARRAY[2,3]);
 array_cat
-----------
 {1,2,2,3}

I need to get result without duplicity!
 {1,2,3}

Thx
Fafi