Do you have to let a company know that you have another job?

I am starting a new job on Monday. I was looking over the preemployment paperwork. I have to sign a doent saying if I have a second job. I do contractual work which is not an every day job. I see people for psychotherapy and get paid per person. My new job is for a large health care system and will be working in a Hospice, not psychotherapy but will be doing some counseling. I don't want to lie, but I don't want any issues to arise as far as working for this company. I was already hired and received my offer letter.