I am currently with two companies contribute to my EPF, I also accept salaries from both companies every month. Since both companies are under my father, uncle and their partners. I've been received EPF contributions from these two companies for 2 years without problem. I also search in Google to double confirm whether it is legal.
According to Section 24 of the EPF Act 1991, yes EPF can accept two companies contributions in the same time.
Besides that, I also use the salary from the second company to do self-contribution into my EPF account.