It seems like your output is not well calibrated.
Which calibration method and parameters did you use for the calibration? (automatic through Vahana VR or manual with PTGui,which FOV did you use?...)
I can also see your 2 cameras are filming in the same direction, while your cameras should be pointing in opposite directions for them to cover a full sphere and calibrate successfully.
Can you try calibrating with the cameras being back to back?
VideoStitch Support Team