Bug in Woo Coupon URL

If you use the WC feature to go to another page after adding a Product & then add another Product + Coupon, only the second Coupon is added

So on a site with Woo Coupon URL installed do this:
1) Add a product + coupon by going to https://WCsite/SomePage/?add-to-cart=1234&coupon=abcd
2) Then add another product & coupon by going to https://WCsite/SomePage/?add-to-cart=9876&coupon=xyz
3) View your cart
4) Products 1234 & 9876 are added ok but only coupon xyz is added

If you add an additional step 1a) and view cart after adding the first product then both coupons are added correctly.