My GC EB 2 is in progress and my 8th year H1 extn is in progress. I am in the last stage of Aussie PR.
In Aussie PR document they asked if I have PR from any other country. For me the answer is "no". But eventually, when I file I-485 for the US, if they ask me the same question, I'll have to say "yes" and in comments mention that I will renounce Aussie PR. Hopefully that'll work. So, I don't knwo the legal or correct answer to your question. But since my visa is stuck at BALCA, I'll ready to take the risk.