Customer Use of Multiple Gift Cards

[Mf@rmC]

I am testing the cart prior to roll out. I attempted to enter two $10 gift cards for a $20 product. It would appear that the cart cannot accept multiple gift cards, even if they are equal to or less than the value of the product. Could you please let me know if there is a way to do this. I tried adding the codes with a comma between "Not a valid gift card number". Thanks in advance for your reply.