Can a consolidation company help me dealing with illegal payday loans?

If that payday lender is illegal, you don't need to pay off any interest for that pdl. So, pay off the principal amount only.
in case, both of your pdls are legal, you may go for approach a genuine consolidation company. They will try to negotiate with your pdl lenders on your behalf to reduce the high interest rates. Moreover, you can make single monthly payments to the consolidation company, which in turn will pay off your lenders.

Yes, but while choosing a consolidation company make sure it's a reliable one. You can check BBB records and customer reviews to choose a good consolidation company.

Are the lenders legal? If yes, then you can go for consolidation. If no, then just repay the principal amount.

Before answering your question, I need the following details:

Name of the state where you live in
Name of the state where the payday loan company is situated
Name of the payday loan company
How much interest rate they are charging
How much you owe in total