It is simply a terrible idea to have more than one ITIN the way it is a bad strategy to have two names insofar as immigration to the United States is concerned. As I have said before, using an ITIN number to work without authorization, pay taxes, sign up for credit cards, purchase cars/homes, etc. is legally a bad idea, but if you are going to be in the US illegally anyway, it is better to have an ITIN number and file your tax return with the IRS. But, why would you have two ITIN numbers?
The great news is that under the provisions of the Obama Immigration Amnesty, working with a fake SS# or ITIN to work are ignored, and you will be approved for RPI legal status as long as you pay all the income tax you owe prior to approval. If you have paid whatever you owed, just attach copies of your tax returns with the immigration application and you are good. For the purpose of the application, though, just use one number that helps you tell a story to the USCIS and when you get approved for adjusting your status to RPI immigrant, go get a valid SSN from the Social Security Office, tell the IRS to cancel your ITIN and transfer your records from the ITIN to the new number.