Is there a difference if a collection agency purchased your default debt or if they where assigned to that deb?

i received a notification from a collection agency about a old debt that i am not even sure is mine. i sent them a request to validate the debt to make sure i actually owe this and it's mine( still waiting to hear back). the notice said the collection agents#1 purchased my default account from CHASE and has authorized collection agency #2 to settle on this account. who actually owns this debt. chase? collection agent1? or collection agent 2.. if ends up being my account who do i settle it with?