Head,
Few limits are set at the level where the item blows up if exceeded by 1 degree or 1 percent. Most limits are based on the assumed number of times they are reached, and the number of hours they are flown. That way, a continuous limit for dual engine is lower than the continuous limit for single engine, since dual engine limits are met exch day, but a real engine failure only occurs rarely, so that higher OEI limit is only actually experienced a few times in the engine's life.
The concept of how limits are set, tested and flown is one of the deep mysteries that needs better explanation, by far. In effect, the user (you) the manufacturer (me) and the regulators (the FAA/JAA) are all in a mutual dance, where the limits define the capabilities of the system as tested to the capabilities as approved. Along with this certification system is a means to assure the aircraft is used in agreement with the tested values (limits marking and training and interlocks) and inspected to assure continued safety (HUMS, data recorders and maintenance manual inspections.) The object of this dance is predictable safe operation.
Want to be confused? One type engine can have 4 different sets of limits, and therefore four different dash numbers, even though the parts are all identical. Each new dash number engine can have different power and different overhaul times. It is possible that the same engine can have different power in different countries (due to different ways to interpret the test data.)
Life was simpler when the rules were simple, but those simple rules were never more accurate, frankly.