MS CRM保存+复制为新（自定义实体）

I have a custom entity in Microsoft CRM (4.0). The user has to input records however usually they have a batch of 20+ records that are almost the same apart from 2 or 3 fields which need changing. I know I need to write some custom code to enable this functionally. However can anyone recommend any methods to do this. I have a custom entity in Microsoft CRM (4.0).