Why is this even possible? This seems like a recipe for fraud :/
Yes. It's perfectly fine. In fact many people increase their chances doing this. Many illegal consultation companies do this too. Very crafty.
I know a person, who had applications from 6 companies. It almost guarantee win.
It’s perfectly legal.
I got an offer from Microsoft and I am thinking if I should let them apply for H-1B or not along with Amazon. Or just let Amazon know not to apply for H-1B. I am a bit concerned.
Talk to the company first. Although it’s legal, most employers won’t be willing to do it.
Yes. As long as they are not related or subsidiaries.