PTP host address loops back through destination?

[Roy Marples <roy.marples%logostechnologies.com@localhost>]

Hi List

I have

pppoe0: flags=8851<UP,POINTOPOINT,RUNNING,SIMPLEX,MULTICAST> mtu 1492
        inet 1.2.3.4 -> 5.6.7.8 netmask 0xffffffff

traceroute to 1.2.3.4
1 5.6.7.8
2 1.2.3.4

Why does this happen? Can I stop this behaviour as traffic for the host 
shouldn't leave the host?

Thanks

Roy