Tires: Safety of repaired tires, safety profile, contaminants

Question
Is there a significant drop in safety of a tire that has had 2 holes patched vs 1 hole? And if so, is plugging with vulcanized plugs preferred and does that offer a better safety profile for 2 repairs vs 1?

Answer
Fred,

Every time something is repaired, it is not as good as new - and that applies to tires as well.  

There is a risk from the hole.  There is a risk because the tire was operated under inflation.  There is a risk for the type of repaired made.

Needles to say, 2 repairs more than doubles the risk.

Plugs are considered temporary repairs because a certain percentage of them leak.  The only approved type of repair is a patch/plug combination, where the plug seals the injured area from outside contaminants, and the patch provides the seal and bridges the hole.