Technically the states that aren't 1 party consent are all-party consent. See Washington's RCW 9.73.030 for an example.
(1)...it shall be unlawful ...to intercept, or record ... without
first obtaining the consent of all the participants in the
(3)...consent shall be considered obtained whenever one party has
announced to all other parties engaged in the communication or
conversation, in any reasonably effective manner, that such
communication or conversation is about to be recorded or transmitted:
PROVIDED, That if the conversation is to be recorded that said
announcement shall also be recorded.
When I announce that I am going to record, then by continuing to talk the other parties are deemed to have consented to me recording (because I am a very trustworthy guy). That does not mean that anybody else can record without likewise announcing that they are going to record, whereby they can consent to this other less-trustworthy guy also recording them.