Override Price
When you see (Override Price) on an invoice line item, this is because the price for a line was set specifically as a total and not as a per unit price. For these cases the unit price is calculated from the total line price divided by the quantity.
If you'd like to hide this notice from invoices, you can turn off the setting by going to Admin -> Billing -> Company Options -> Formatting -> Invoice Format -> Show Override Price Text If Price Overridden.