immigrant visas to 2 different countries?

It is not a problem with the applications/petitions; but with the employers that will be offering you a job and paying all of the associated fees for the petitioning. You are going to be responsible for the fees if you select the other country to go to. And some of the agencies/employers have cancellation fees of close to $30,000 US plus.

If you are willing to pay the cancellation fee to the employer for the US, then go for it. You need to be aware that you will be legally responsible for all fees as well as the time that they spent on preparing your paperwork as well as attorney fees and they will go after you to their money back. So this can make it much harder for you to ever get to the US.

I would most definitely discuss this with the employer for the US before you do a thing.