dynamic dns - omitting duplicate names

[Barnaby Scott]

I have a network that uses DHCP and with which I would like to use dynamic
DNS. However when I tried dynamic DNS, I found out that some hosts were
reporting themselves with duplicate names. Obviously this makes a nonsense
of DNS and was causing errors to be logged, so I want these to be omitted
from the dynamic DNS updates.

Unfortunately I can do nothing about these boxes giving duplicate names,
and they are completely unimportant on the network (being only music
players). They need IP addresses assigned and that is all.

What is the most sensible way to overcome this? Ideally it would be great
to have a configuration which effectively said:
 'put everything into DNS unless it gives its name as ...'

Have I missed something obvious?

Thanks

Barnaby Scott