new Random() uses the current time as the seed value. Thus, if you are calling this function multiple times in a very short time span, it might return the same value. Here's the explanation from MSDN:
The default seed value is derived from the system clock and has finite resolution. As a result, different Random objects that are created in close succession by a call to the default constructor will have identical default seed values and, therefore, will produce identical sets of random numbers. This problem can be avoided by using a single Random object to generate all random numbers.
