Here's a randomly chosen image from Oriental Motor, showing a typical torque speed characteristic for a stepper motor:
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https://www.orientalmotor.com/steppe...er-motors.html

If you gear down the output by 2:1, you might move from eg 500rpm to 1000rpm and in the process you'd drop from a pullout torque (loss of position) of ~45oz-in to 27oz-in (forgive the Mercan units). After the supposed doubling up of torque through your expensive reduction stage, you'd actually end up with ~54oz-in. That's an increase of ~20%, not 100%. See what I mean? Some of the Chinesium steppers have even worse torque curves. Sure, you double the stall torque but unless you plan to use your machine as a press, that's not much use to anyone.