We present DualVib, a compact handheld device that simulates the haptic sensation of manipulating dynamic mass; mass that causes haptic feedback as the user's hand moves (e.g., shaking a jar and feeling coins rattling inside). Unlike other devices that require actual displacement of weight, DualVib dispenses with heavy and bulky mechanical structures and, instead, uses four vibration actuators. DualVib simulates a dynamic mass by simultaneously delivering two types of haptic feedback to the user's hand: (1) pseudo-force feedback created by asymmetric vibrations that render the kinesthetic force arising from the moving mass; and (2) texture feedback through acoustic vibrations that render the object's surface vibrations correlated with mass material properties. By means of our user study, we found out that DualVib allowed users to more effectively distinguish dynamic masses when compared to using either pseudo-force or texture feedback alone. We also report qualitative feedback from users who experienced five virtual reality applications with our device.