Two-dimensional digital predistortion (2-D DPD) is one of the most commonly used approach to linearize the concurrent dual-band radio frequency (RF) power amplifiers (PA). In this paper, we propose to determine an optimal structure of a dual-band DPD model using an optimization-heuristic-based method. A new form for 2-D DPD is proposed for lower complexity. We propose a search criterion based on generalized information criterion which represents the trade-off between the DPD linearization performance in two bands and its model complexity. A comparison against a compressed-sensing-based method is also made. The effectiveness of the proposed method is validated with two 20 MHz long-term-evolution (LTE) signals on two carriers with 100 MHz frequency separation.