In some mail I received from Duncan McEwan, sie wrote
> 
> I've just tried twice to install NetBSD in a spare partition on a disk
> currently containing FreeBSD.  Both times, the installation of NetBSD
> clobbered FreeBSD (at least to the extent that it would no longer boot -
> I don't believe it had actually overwritten the contents of FreeBSD
> partition, since I was careful in specifying cylinder counts, etc).

*Maybe* if you installed FreeBSD on the second 386BSD partition, but
NetBSD can only recognise one (and it is always the first) 386BSD
partition type on a disk (maybe editing disklabels will help avoid this
situation, but typically when you install, you don't quite have the
right environment yet available to do that).