Can I resolve 2 websites, on 2 IPs on same Pi as Pihole?

What do you mean with outside ?

pi@noads:~ $ cat /etc/hosts
127.0.0.1       localhost
::1             localhost ip6-localhost ip6-loopback
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters

127.0.1.1       noads.dehakkelaar.nl

0.0.0.0 wpad wpad.dehakkelaar.nl
:: wpad wpad.dehakkelaar.nl

192.168.1.173 a.ddns.net
192.168.1.174 b.ddns.net

pi@noads:~ $ sudo service pihole-FTL reload
pi@noads:~ $

From a client:

C:\>nslookup a.ddns.net
Server:  noads.dehakkelaar.nl
Address:  10.0.0.2

Name:    a.ddns.net
Address:  192.168.1.173

C:\>nslookup b.ddns.net
Server:  noads.dehakkelaar.nl
Address:  10.0.0.2

Name:    b.ddns.net
Address:  192.168.1.174

Better not touch local.list and see below:

If select below option, the IP and interface in setupvars doesnt matter: