I got billed by both DHL and UPS for same shipping

Hey everyone, I’m waiting on my package from Korea. Right when my package was sent I got email from DHL to pay duty (around 30$) which I paid right away and one day after got email from UPS saying that I have to pay duty again! That bill is 70$ which I still haven’t payed because I don’t know what to do, should I contact them somehow or is this all okay? Take into consideration that I paid 100$ for my package, and that would make it double the price then. I would appreciate if somebody could explain me how to handle it. It is my first time ordering from Korea.