Everstart batteries are made by Johnson Controls. Their full charge voltage is 12.65V. The higher voltages you are seeing are what is called surface charge, which is a remnant of the last charging voltage being applied by the charger. Surface charge dissipates at a much faster rate than actual battery discharge.
The battery above 13V is in good shape, though it says nothing about the actual capacity of the battery. The other one is probably toast, but it could be salvagable.
What does the electrolyte level look like in the cells of the suspect battery?
If electrolyte is okay, you may need to equalize. It would be good to check cell specific gravity with a hydrometer or a refractometer before and during equalization. Cells can become unbalanced and equalizing can help with that easily.