Hong Kong Visa. Thank you so much.

My friend just submitted her application for her Hong Kong visa at Chinese Consulate General at Houston, TX. They kept her Vietnam passport and also her copy-passport. She is US resident and also has green card. They said it might take up to 2 months. Her application had all required documents. But they said they are not guaranteed for Hong Kong entry permit. Can I have some explanations for it ? And why they take her original passport while they also have her copy passport?