Sounds like Light & Shadow, but it isn't princess but just a noble's daughter. Though, they sent the servant who isn't exactly who they thought she is.
I guess was that... Mangago don't have, right? I can find anywhere
Here it is. http://www.mangago.zone/read-manga/light_shadow/
Thank you so much!
No probs. Happy to help!
she was taken to marry the tyrant lord; upon arrival, as soon as the lord see her, he realizes that the princess who going to be his wife was not that woman in front of him, that woman was the princess's servant