awk problem

[Len Conrad]

I readfile or pipe this text, in any line order:

rm90.steampick.info
fgce172.lanejive.info
smailer1.service.govdelivery.com
fl49.orangetalon.info
pollux.carespecial.info

into a program to remove subdomains down to domain.tld :

awk 'FS="." { print $(NF-1)"."$NF }'

and get the first line doubled rather than processed like the other lines:

rm90.steampick.info.rm90.steampick.info
lanejive.info
govdelivery.com
orangetalon.info
carespecial.info

thanks
Len