Here is some defferent opinion from:
http://www.hooyou.com/j-1/j1_2year_rule_faq.html
Q: I came to the U.S. with a J-1 visa subject to the two-year rule. Can I change my J-1 program?
A: It is not a good idea to change your J-1 program if you have not yet fulfilled your two-year requirement. If you change your J-1 program, you may be subject to the two-year restriction twice and will need to obtain two J-1 Waivers in order to be relieved of the rule.