Invoices displaying dual currencies

Would it be possible to have invoices showing dual currencies? I would be a simple way to issue invoices in right currencies without to have to adjust all prices from the price list one by one. Also the counter value is always true regardless of the exchange rate at the time of payment.

This would not be possible, because changing exchange rates would affect the relationship between prices in the two currencies. So the balance of Accounts receivable would constantly be fluctuating. Set up your customers in the currency in which they will pay.

Not if the exchange rate is set within the invoice like a discount for example and the value is given as a reference. If it is set as a global setting it will affect it all and will not manageable.
If the currency is set for each customers as you suggest I would need have a list price of each items for each currencies?
Also let’s say it is doable how would the prices in different currencies would evolve against the current exchange rate?

Yes.

They would not evolve. The price you enter when defining an inventory item is a number that is used in whatever currency the customer is defined in. So if the price is 89 and you enter it for a customer denominated in pounds, the price is 89 pounds. If you enter the same item for a customer denominated in dollars, the price will be 89 dollars. So prices must be edited to account for exchange rate differences. Or else, you need different inventory items in different currencies. Regardless, they will change only when you edit the inventory items.

That is exactly what I thought. It would be nice to have under the invoice/Proforma/sales order a way to display a different currency. The exchange rate should be set individually on the day and should remained independent to the global exchange rate. Otherwise each items needs to be created in different currencies and the fluctuations of the exchange will made each price outdated on an hourly basis.