Doesn’t matter. The Constitution says only that the President of the Senate shall . . . open all Certificates and the Votes shall be counted.”
Now, EVERY state has two sets of electors (maybe three if an independent has gained a lot of support). The controversy arises over which set of electors the veep opens. The implication of precedent is that he has the authority to “open” or “not open” any certificates he deems improper, fraudulent, or otherwise tainted.
The 20th Amendment in no way speaks to any of this; does not in anyway address the precendent of 1796 or 1800. In fact it has nothing to do with the veep’s powers/authority. In 1876, the states DID certify their slates, which the veep DID NOT ACCEPT. Again, 20th says nothing whatsoever about that.
If the VP only has one sealed envelope from any given state, there's no question about which one gets counted.
Other sets of electors can be sent from any given state. In 2020, only one of them was properly sealed by a person authorized to act on behalf of the state in question. This is why it was of utmost importance for someone else in a position of authority in a contested state to inform Congress about a disputed slate of electors. That could have been done by a governor, a secretary of state (if duly authorized to act on behalf of the state), or -- better yet -- a formal act of the state legislature. NONE OF THIS EVER HAPPENED.
Sen. Tom Cotton's public statement about why he would not support any objections to the certified electors on January 6th was very instructive in this regard. He made it clear that he would have had no problem objecting to the electors from another state, but only if someone acting in an official capacity on behalf of the state notified Congress of a disputed slate of electors.
He closed his statement with a warning: If objections like this in the joint session of Congress become routine, then the U.S. would become a de facto parliamentary government where the President is elected by Congress.