DC, how are those two ways? The case of R Akiva definitely proves that it is appropriate to identify a living individual as Moshiach when it seems to be the case, even if it might still turn out otherwise. But the fact remains that Bar Kochva was <i>not</i> Moshiach. Therefore R Akiva’s identification of him as Moshiach was mistaken. Surely you don’t dispute that. You don’t still expect Bar Kochva to return and be Moshiach. Maybe his neshomo will be in whoever does finally come to redeem us, but the actual person who is Moshiach will be someone else.
What the Rambam is telling us is that even though R Akiva was mistaken, he did the right thing, and if the same circumstances were to arise again the next day he would have done it all over again, and not been afraid to make the same mistake twice. And that we should do the same, and not be afraid of being mistaken.