Apple Inc. is preparing to unveil successors to the iPhone 6S and iPhone 6S Plus as early as next month with more advanced photography capabilities and upgraded hardware in a design similar to that of last year’s models, according to people familiar with the matter. The standout features will be a dual-camera system on the larger iPhone, a re-engineered home button that responds to pressure with a vibrating sensation rather than a true physical click and the removal of the devices’ headphone jack, said the people, who didn’t want to be identified discussing unannounced features. Apple declined to comment.