You really need that because if you have only one copy of something, you don't have a backup; so, you can store the one copy separately.

你真的很需要这项发明,因为要是你只有一份的话，你就没有备份;,这样的话，你就可以将副本单独留存。

耶鲁公开课 - 金融市场课程节选

You can't have just one copy; you have to have multiple copies.

你不是只有一份副本就够了;,你得有很多份才行。

耶鲁公开课 - 金融市场课程节选