First, no way you can hide that you have multiple H1B from the immigration officer.
Second, you can work full-time for one H1B, then work part-time for different employer(s).
Not sure if you can work two full-time. But one full-time, one part-time is definitely OK.
Second, you can work full-time for one H1B, then work part-time for different employer(s).
Not sure if you can work two full-time. But one full-time, one part-time is definitely OK.