visit Vietnam 2x within 3 months

Dear madam, sir,
My daughter arrived in Vietnam on march 29th, she intended to stay for 2 months. She got her visum via fast track (excellent service!). Due to circumstances she will fly to New Zealand on April 9th. She would like to fly back to Ho Chi Minh City on June 1st. Does she have to apply for a new visum? Is there a problem to apply again or a new touristvisum?