One option is to change HN accounts often. Every few posts you need to make a new one. Successfully correlating writing styles needs some data and if there are only a few sentences to go off then that's not enough.

I know that the site guidelines discourage that, but what can you do.

I guess you can try to develop two very distinct writing styles.

Or, as I do, consider everything posted to HN to be linked to me. My handle is actually an abbreviation of my full name. I consider HN to be "professional" correspondence.