I have dual citizenship (one by Birth) and the other is Australian. I have lived in Australia for the majority of my life and I only have 1 passport. On the ESTA website there is a question for dual citizenship. If I choose yes you must enter the passport number for the second citizenship.
Can I still obtain a visa with ESTA ?
From the ESTA Online Help:
What if I have dual citizenship, but my non-VWP passport is expired or I do not have a passport for that country?
If you have any additional passports, please enter the most recent passport information, even if that passport is expired. If you are a dual citizen but do not have a passport from another country, select the country from the drop down list and do not enter anything in the Passport Number field.
