This won't work.  Linux will consider both addresses as local to the
host and will never respond to arp requests from any of those addresses.

See http://en.wikipedia.org/wiki/Host_model

According to this Linux defaults to the 'weak host' model (I don't
know if Ubuntu changes this default). Although I don't know why this
will matter because I'm sending packets destined for the IP of that
specific interface (which should work in strong and weak models).

I think I'll sift through the ARP processing code to see if there are
points where it can drop a packet.

You might be able to change this by tuning arp_announce/arp_ignore - But
I don't know if that changes the behaviour wrt responses to local
addresses...  See
https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt for
the meaning of these knobs.

I'm playing around with different combinations of anything even
remotely connected to ARP and routing. Nothing's changed till now.

Thanks for your time.

-mandeep