Yes, the emergency wage subsidy could be used to pay the salary of an employee who receives the Canada emergency response benefit. After the two programs were launched, a change was made to the CERB so that claimants could earn $1,000 in salary over a four-week period without losing their benefits.
Businesses could file subsidy applications in connection with the salaries they were paying their employees. In that case, we're talking about the $1,000 that businesses paid their employees. So the two subsidies could have been paid in respect of a single employee.
However, one of the two is paid directly to the business. It provides indirect financial support to an employee, whereas the other benefit provides direct support to that employee. You have to distinguish between the two measures. The emergency wage subsidy is paid to the business, whereas the Canada emergency response benefit goes directly to the individual.