Hello,
I will add a patch but I need to tell you that your test case is flawed.
A classical account would be create via an HikaShop registration, which include the billing address.
And when a customer have a billing address in the database, that address is automatically used in the cart.
Now, if you exchange the billing with the shipping ; you got something more logical and cases which could happen.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.