Legal Question in Real Estate Law in Pennsylvania

Yes. If the lender who foreclosed is suing, they are seeking a deficiency judgment if permitted (PA does allow it but some states do not). If you are being sued by a second lender who did not foreclose then you are being sued on the note.

In either case, you either need to talk with a real estate attorney if you think you have defenses or, if you don't, then you may want to talk to a bankruptcy attorney.