Transactions can have only one foreign currency at a time.

Good observation, Monica-nordstrom. 

You can only assign one currency to each account, suppliers, and customers. The transaction's currency is based on what's set up on their profiles. Although, it will also give you the equivalent amount in your home currency.

I'll share the reference about Multicurrency so you'll know more about the feature. 

We'd be happy to fill you in if you have more questions. Just leave a comment below.