Okay, unfortunately, you're on the hook for BOTH (meaning, they can and will be on your reports for at least 7 years after the filing date).
What happened is that the creditor (assuming the lender), in order to be able to enforce the judgment, filed in IL (I'm assuming the lender's "home state") and then domesticated the judgment in CA. They often do that in order to prevent the judgment from falling out of SoL. They also do that so they can attach liens, garnish wages, etc (which, BTW, they can't, in most cases, do with a judgment filed out-of-state).
As it is, your SoL will be 20 years ... but it IS renewable for another 20 (and often, if a creditor goes to the trouble of domesticating a judgment, they WILL renew it). So what that means is they have 20 years to seize your assets, garnish your wages, and/or attach liens.
I would honestly pay it NOW. Or at least try to come to some sort of accord/agreement. Otherwise, one day you might wake up to find that XYZ Lender has taken your paycheck and/or attached a lien to your home.