It's possible to have two H-1B employers, one based on full-time employment and another based on part-time employment. This is referred to as concurrent H-1B employment and it requires two approved H-1B petitions.
A lawyer once explained to me that there needs to be an employer - employee relationship. Basically, there needs to be a possibility of being fired. So if you have total control of a company the H1B visa would not be possible.
Not a lawyer: Yes, as long as there is an employer-employee relationship. Meaning, someone in your company should have the power to fire you, usually a Board of Directors.
