Does the access token change after refreshing?

Hi, I've been trying to test authorization, and making sure my application refreshes the access token as described in OAuth2 Authorization Code Flow at this link here:  https://v3.developer.constantcontact.com/api_guide/server_flow.html

I am testing, and trying to refresh my access token as described in step 8, but am sending my request "early" (before waiting for the access token to expire), and am getting the same access token back in the response. Is this expected behavior? I was expecting a different access token each time.

Thanks!