The article presents new findings on arc stability in twin-wire robotic arc welding corresponding to the torch orientation and electrodes' position. The two mutually influencing co-existing arcs affect the stability of counterpart arc, and thereby alter the weld bead properties. The complex interaction between the arcs is determined by multi-resolution time-frequency spectrum using wavelet analysis. The wavelet-energy-entropy of the signals are analyzed to quantify the arc stability. Several experiments are conducted with different combinations of welding currents at primary and secondary electrodes (vis-a-vis one who initiates and follows the arching sequence, respectively) in tandem and transverse orientation of the torch. The investigation divulges that electrode positions and torch orientation significantly impact arc stability which in turn impacts the heat input and weld bead geometry. The arc penetration in tandem orientation is augmented by the secondary arc that operates in the same weld pool. While the transverse orientation improves the arc stability and facilitates a wider weld bead with reasonable weld penetration suitable for applications such as wire additive manufacturing and cladding. An approach for predicting arc stability as a function of process parameters is a significant contribution from this investigation. The insight into the arching phenomenon in twin-wire gas metal arc welding due to the investigation is expected to help the machine builders to design an appropriate controller that minimizes arc interference. © 2020 The Society of Manufacturing Engineers