Yes

Remember — as long as Beverly's conduct is lawful (which, in this case, it is) and as long as Beverly continues to do her job well and without problems, you really have no grounds for asking her to give up her other job.

Some would argue that if customers knew about Beverly's other job that it would harm the business's reputation. In this case, however, Beverly only deals with customers over the phone. The chances of customers figuring it out are probably small.