Hello
I think you just want to sort the field#1 and NOT Field#2 and Field#3 along with it.

sort.GIF

now if your sorting that includes fields#2&#3
your sort is correct (it's not duplicating the field it's that its the correct values that goes along with the sorted field#1..

as a proof i extracted (thru copy/paste this 4 consecutive sorted values #1#2#3 fields)

A,S,M, Werbeagentur GmbH (ASM)	info@asm-muenchen.de	www.asm-muenchen.de
AGENTA Werbeagentur GmbH	info@asm-muenchen.de	www.asm-muenchen.de
Aimaq von Lobenstein Creative Brand Consulting GmbH	info@asm-muenchen.de	www.asm-muenchen.de
argonauten G2 GmbH	info@asm-muenchen.de	www.asm-muenchen.de
they have really same fields #2 and Field#3 values

hth.