MarketPress coupon failing with error about totals

I have a single product only and one price inc delivery. When a discount coupon is applied successfully and the checkout reaches out for paypal I get the following error:

Oops! An error occurred while processing your payment.

10413 – The totals of the cart item amounts do not match order amounts.

The totals of the cart look wrong:

Product Total £149.00

Coupon Discounts –£30.00

VOUCHERCODE –£30.00

VAT £29.80

Order Total £148.80

Looks like the discount is showing twice but applying once and therefore not adding up.

Is this a known error again?