It depends on the layout and operating conditions.
Sometimes, a single via will be limiting your resistance, voltage drop, or RC delay - in which case, you want to double (or quadruple) the number of vias.
If via contribution is small, then it does not make sense to double it (unless this improves the yield) - it may increase parasitic capacitance.
Proper EDA tools will tel you how critical this or that via or group of vias is, for your characteristic of interest.
This may be especially important for optimizing low-capacitance nets, like pads for high-speed signals, to minimize net capacitance (ESD diodes plus parasitics), without affecting resistance and current density for ESD.