In Magento orders ship to name sectioin, last name appears twice

I got a problem from the Magento(1.9) website after the customer paid the bill via paypal express.

it seems like that Magento is assigning the full name to the first name field in the first place, and assigning the last name again.

So I got the issue shown in the following picture. The billing address customer name is correct, but the shipping address customer name is duplicated.

Thanks for your help in advance