I'm installing the one for the armor, and I already extracted one of them to the data folder. Now this other one I'm about to extract has the exact .esp file in it called H.E.L.L.U.V.A._Merchant_Containers that I just extracted from the previous helluva mod. Do I overwrite the old one with the new hullva merchant container.esp file? Do I keep doing it with the other same esp files?

You only need one. It's there with every helluva mod because they all need it, but it's the same file.