any chip can measure up to the limits of the map sensor fitted (so long as its the correct map for the chip, simply plugging a 3bar onto a standard or stage 1 will not allow it read to 2 bar for example. it will be unable to interpret the signal it receives correctly).
as such a standard chip can measure up to 1bar above atmosphere (and -1bar vaccum hence the 2bar designation).

where the difference lies is in how the chip are mapped to deal with these readings.
a standard chip is set to run with boost of 0.7bar, about 10psi. anything above this is outwith its optimum range and it cannot adjust fueling to take advantage of this extra pressure up until 1bar limit where it will shut off....rather suddenly. its very possible to wind up your boost with a standard chip to the limit of 1bar, the chip can after all read it and the extra pressure certainly makes it feel quicker. the issue is that it will most certainly run lean and will also be less than optimum

using a stage 1 chip will adjust the settings so that boost can be increased to this 1bar ceiling AND the fueling etc is increased to deal with this. this results in more power and better performance since readings are all within an accepted range.

as such you cant use the boost reading on your car purely to gauge if its been chipped or not. a reading of 1bar, the max setting for stage 1, would be an indication that it was chipped however since the boost setting is a mechanical function and entirely independent theres many other factors that could be contributing instead, ranging from a fault or leak to simply a previous owner increasing boost with little regard for the car itself.

why dont you just take a look at the ecu. if its never been opened its safe to say its not chipped. if it has been why not open it up and look at the chip thats in there. it should quickly become apparent as to whats in there or not.