How do you put in two separate email address's for one invoice?

Welcome to the Community, @lori74. I'm here to walk you through entering multiple email addresses in the Customer information so you won't have to add it in every invoice. 

All you need to do is to use a comma to separate the email addresses. Example: abc@yahoo.com,def@yahoo.com. 

Here's how: 

1. Go to the Sales tab, then choose Customers.
2. Select a customer.
3. Click the Customer Details tab, then click Edit.
4. Enter the email addresses in the Email field.
5. Click Save.

Please know that there's a limited number of characters that can be entered in this field.

For future reference, read through this article: Create templates for recurring transactions. It helps you learn about adding different email addresses for a customer when creating any sales forms. 

I'd be here to help if you have additional concerns. Take care.