当然是有的.
这里只有1个主语,却有2组动词:neglect/practice 和 harm,它们之间没有联系(词),所以是个病句.可改成:
Party B's neglecting the duty seriously or practicing graft consequently harms the benefits of Party A.
或:
Party B neglects the duty seriously or practice graft consequently,(it) will do harm to the benefits of Party A.