One for the HN alternative, and one for the sub-optimal HN alternative. When people flood the new HN with poor material you send them over to the less moderated site.
There are plenty of sub-optimal alternatives - I just don't want to name them.
A lot of people who create alternatives have way too much confidence in "the launch". It's better if they actually have a good community to show for it instead of some glorified CMS with "potential".
Hacker News like success stories, so that would be a good angle to promote a new community with - rather than announcing an inconsequential launch.
One for the HN alternative, and one for the sub-optimal HN alternative. When people flood the new HN with poor material you send them over to the less moderated site.