Well, I'm often confused, but I don't think I'm confused about this.
First, it's not true that the USPTO "will not consider common law TM rights..." Section 2(d) of the Lanham Act provides that a mark will be refused registration if it:
(d) Consists of or comprises a mark which so resembles a mark registered in the Patent and Trademark Office,
or a mark or trade name previously used in the United States by another and not abandoned, as to be likely, when used on or in connection with the goods of the applicant, to cause confusion, or to cause mistake, or to deceive...
emphasis addedNow, it is true that it is extremely unlikely that the USPTO will refuse a mark under Section 2(d) of the Act if the cite is not registered, and JS is right that the in a case like this, the first to file will likely be granted the Registration, but it's not true that the USPTO
will not consider unregistered mark on the off-chance that the become aware of it - they have to, it's in the statute. There's also the possibility of 2(a) False Association refusal, but that requires the USPTO to prove the higher "known for" and "affects the purchasing decision" standards
No, I was not suggesting that the NP could remedy the situation by registering the mark somehow over the previously registered mark. That's why I said"..in the first place..." meaning before the other mark registered. Sorry for any confusion (and sorry about that Wolverine problem

)
The "you know how lawyers are" crack was supposed to be a joke - that's why I added the winking smiley face as a kind of joke alert, since I can see lawyers read this thing. It was just meant to be a tweak. Sorry if you took offense.