PhD in the US with an MSc from another country: coursework exemption?
It depends on the department. I have been looking at various applied mathematics departments in the USA and all of them want PhD students to go through the coursework and obtain an MS, even if they already did a masters degree before.

I think in general, there is no chance to skip coursework. This is probably because different universities have different standards and syllabuses for the same course. And they want to ensure everyone is up to the same standard and have taken the same syllabus.

But do check with the department, there are always exceptions.

P.S.

However, it doesn't have to be a "waste" of two years. The level of the course might be higher and you are probably able to choose different courses to get broader experiences. If all else fails and you are able to ace all the courses with no problem, you can always spend the extra time looking for a thesis adviser or find research collaborators.