Example you hit twice with Tidefall, will there be 2 wounding dots on target assuming you hit twice within 5 seconds? or does the dot just get refreshed by the more recent hit?

My understanding is that dots from the SAME source never stack, but ones from different sources do.  So you'd need two different weapons, each able to apply a DoT, in order to have two weapon-based DoTs

I'm pretty sure that wounding does stack I used Tidefall my entire playthrough and it seems like it, pretty easy to test, I would but I'm heading to bed right now.

I never saw more than one "Tidefall" affliction on the enemy.