Is obtaining Multiple PhDs in two different and barely related disciplines detrimental to the career?

I think you're planning too far ahead, and are definitely overthinking this. Most people find a PhD a pretty grueling process, generally well beyond expectations. My feeling from having gone through it myself, and knowing many others who have, is that the odds are very high that you'll have no interest in going through it a second time.

Get a PhD in the field you actually want to work in. Finishing a PhD is hard; finishing a PhD in a field you're not very interested in is even harder. Put your energy into doing one field well, rather than spreading your energy out and doing two fields at a lesser level.

But to disregard that and answer your question, I think people without PhDs would probably be impressed, while people with PhDs would think it very strange, and not necessarily good. But I suspect there would be pretty wide variance in opinions, depending on surrounding circumstances.

Edit: I should add that Master's Degrees make a pretty good supplement to PhDs. So if you finish this MA in Education and then move to a different field that you can plausibly supplement with Education, that would be normal and probably pretty effective. But again, plan to do your PhD in a field you're interested in.

To be honest, your internal reasoning would be invisible to me. Why you did what you did can be speculated about, but you don't need to reveal it.

Many people change fields. The difference between Education and data science is wide enough that most of us would just assume you had a change of plan. Nothing wrong with that.

But, of course, your plan may fall through, and your plans may change. But for the main question here, don't worry about it. Worry about doing a good job in moving toward and evaluating your goals.

I might worry more about someone who had don't degrees in two very closely related fields. In such a case, the first degree gives you the skills to be productive in that field and in the related one. I might worry that you just wanted to be a perpetual student. But Education and STEM use different research methods and require very different insights. Having two degrees, either for changing fields or for wanting to work at the cusp, seems much more natural to me.