PT symmetry-based wireless power transfer (WPT) systems can achieve nearly constant output power and transfer efficiency within a coupling region, but their practical implementation is limited by strict parameter matching and poor adaptability to unequal load losses. To overcome these limitations, this paper proposes a global quasi-PT symmetric modeling method for a single-transmitter, dual-constant-power receiver WPT system. Unlike classical PT-symmetric models that impose strict symmetry on individual receiver branches, the proposed model treats the entire secondary side as an equivalent subsystem. Therefore, quasi-PT symmetry is established by approximately balancing the total secondary loss with the primary gain, rather than by enforcing identical branch losses. Based on this global model, the frequency-splitting behavior is analyzed, the strong-coupling condition is derived, and the permissible ranges of the quality factor and inductance are obtained. Theoretical calculations show that the allowable ranges of both $Q$ and $L$ under quasi-PT symmetry are approximately three times wider than those under classical PT symmetry, significantly reducing the requirement for parameter precision. Further analysis demonstrates that, under global quasi-PT symmetric strong coupling, the system can maintain near constant efficiency even when the two receiver branches have unequal losses. This relaxes the conventional constraint of precisely matched receiver losses and improves the flexibility of multi-load WPT operation. In addition, for the secondary coplanar coils, the transition from far-field coupling to near-field coupling is investigated, and a boundary-distance formula is derived. When the distance between the secondary coils is smaller than this boundary distance, the influence of cross-coupling on power distribution is further analyzed, providing guidance for receiver coil layout optimization. Experimental results verify the proposed theoretical model and analysis. The proposed global quasi-PT-symmetric method improves parameter tolerance, supports unequal receiver losses, and offers a practical design framework for robust multi-load WPT systems under variable operating conditions.