In real life, I think we'd probably glean some insights to the soul in the development process. Like say, if one of the first human test subjects goes through it, only to have their personality irrevocably changed, and no one can identify any external reasons why, then that would warrant further research before billions of humans start using it and it becomes an actual problem.

I think part of my "resistance" to this question is that by default, I'm approaching it from the assumption that I'm living in some hypothetical world where a teleporter is as common and everyday as a car or train, and extrapolating from there, so a lot of the hypotheticals don't exist for me because I'm imagining public use. "What if someone puts the version of you that didn't teleport in their basement" well then they would have to coerce me out of the presumably public location for teleports between cities or wherever, because if I step on a pad expecting to be halfway across the globe in two seconds and instead I'm still in the same room, I'm not gonna leave until it's explained to me what went wrong and I'm given assurances for future service and compensation for the failure that already happened.

"oh well what if it only created copies of you" well then it probably wouldn't supplant any existing forms of transportation :), and of course then I wouldn't use it to get around.