Currently I am not in a good relationship with my research advisor and I do not think it will be good as previously. So I decided to change my research advisor if it's possible. Would you guide me how I can find another research advisor? Is it possible to have two PhD advisor?
If you feel you must change your adviser, it is essential that you speak to the adviser before discussing the possible change within anyone else in your department. It is best to be as honest as possible, since usually advisers are experienced in working with students, and do not appreciate an explanation that might appear ingenuous. Also, your request could reflect poorly on your adviser if you speak to someone else in your concentration. I would sit down and carefully make a plan of action to use in bringing up the subject. In addition, try to learn as much about your adviser as a person. For example, is he or she vindictive, intolerant, considerate, etc. That will help you frame the way you approach the subject.
How can I find another research advisor?
The finding part ought to be the same as the one for finding your first advisor. As this would be your second supervisor, your approach should be slightly different. As @AllanG pointed out, you ought to be truthful with regard to why are you making your change.
This post should be helpful for this part of the question: How can I find a second supervisor?
Is it possible to have two PhD advisors?
Yes. You can have a joint supervisor or an auxiliary advisor. Joint supervisor/advisors are especially common when doing an off-site or industrial level research project where there would be an advisor who would help you on-site and the primary one in the institution. If you are doing an interdisciplinary research concerning fields across two departments, then you can have two advisors, one for each department with one being the primary and the other the auxiliary. There are other ways too, but it also depends strongly on the institution guidelines.