You can't convert mono to stereo. You can record the same signal to 2 channels but that is not stereo. Stereo mics are recommended for ensemble music and ambient recording. Mono is preferred for dialogue. Rode does make a bulbous stereo videomic. But the pickup pattern is omnidirectional. Their mono shotgun videomics are much more popular because the pickup pattern is suited to noise rejection. To get more flexibility with your Rode, consider getting the Azden Cam-3, an inexpensive credit card -sized mixer that allows three mics to be connected at the same time. You can record different mics to different channels or both channels. Or wait for a cooler Beachtek version, which I cannot divulge too much of.