I imagine it would be a problem in the US too, just for other reasons probably. You are essentially giving confidential work info to a third party that has no relationship with your employer.
Not a lawyer, but I don't see a deception charge for "under-performing and getting fired for it (while having 2 jobs)" faring well in courts.
Think about it: if you were performing your work well, despite having 2 jobs, what would the deception be? You promised to deliver work on your own, you deliver it on your own. The other job has no intersection with your other one, they are entirely independent. The only difference between that situation and the same situation but poor performance is literally just your performance. Poor performance doesn't automatically turn that situation into deception.