Cross-Technology Communication (CTC) is an enabling technology for efficient coexistence and effective cooperation among heterogeneous wireless devices by exchanging data frames directly without gateways. Recent advances in the physical-layer CTC achieve thousands of times faster speed than that of previous packet-level CTC techniques. However, physical-layer CTC still faces the challenge of inherent unreliability due to the imperfection of physical-layer signal emulation. Our work, named TwinBee, aims to recover the intrinsic errors of physical-layer CTC, by exploring chip-level error patterns. This is achieved interestingly without even observing the chip information and without any hardware modification. System evaluation shows that our key idea, namely symbol-level chip-combining decoding with soft mapping, significantly improves the Packet Reception Ratio (PRR) of the physical-layer CTC from 50%-60% to more than 99%. We also demonstrate the reliability of TwinBee in a data dissemination application over a network of 20 TelosB nodes, achieving over 40x reduction of data dissemination delay compared to Deluge.