How to set different product prices for different shopper groups in VirtueMart?

[kalanithi]

How to set different product prices for different shopper groups in Virtue Mart 3.0.6.2?
This is Product SKU: 210-ACZE
I have Add New price in "Singapore Price & United state Price" only save&close that, After I open "210-ACZE" Automatic created in 3 times "United state Price " prices and Base Price.  why? how to Solve???  please tell me
I have below attached the my issue screenshot ..

Joomla 3.4.0
Virtuemart 3.0.6.2
Php 5.3.28