Are their two Nates in Gossip Girl?

I was watching the first episode and Nate had semi-long hair. then their was a jogging scene where chase crawford, the actor, had short hair. so i thought that was a different character. and at the end of the first episode Nate with the long hair showed up again. well then i watched the second episode and got confused because blaire called the short haired guy nate and sweetie. but at the brunch he had long hair again! sorry if its confusing just bare with me :) i have no idea with this one so i need help!