Hmm... a second hero?! Level up a second hero?!?!? Not level up Wisdom?!?!? The only thing additional heroes need is +resources and Economy. Maybe also Navigation + Scouting + Logistics, but that would only result in a scout who can transport an army from the castle. Making two combat (meaning attacking) heroes is, in my opinion, just stupid. Unless that's what was meant...

Wisdom is only not worth leveling up in cases where there is literally "no" magic, which mainly applies to offline modes, but even in a normal scenario, there can be something like a Sphere of Inhibition, i.e., all magical skills are useless.
Additional heroes need more than just "+resources and Economy."
Logistics has always been related to the main hero; even if it doesn't matter in battle, the speed of catching up to the enemy means a lot ;), and scouting is the job of a secondary hero, usually an accompanying one; navigation is naturally not for the main hero – go ahead, explore, and have a secondary hero do it; no one is stopping you.
No one is suggesting you make two combat heroes; play as you see fit, and there's no need for two main heroes, except in cases where there are 2 opponents, for example, and to save time, you take 2 heroes and send them in different directions to defeat the opponent :) -
that's what was meant ;)