Just for curiosity sake, I looked at the standard RNG in C# and it is indeed flawed, but probably not enough to be seen unless you are doing formal tests.
In [1] it says that numbers have a 0.5034 probability of being odd due to rounding errors in the algorithm that picks a number in a range, which is unacceptable for a simulation, but may actually be better than a real coin toss [2]. The raw RNG is also flawed but not that badly [3]
Okay, now you made me want actually look into that ;) I should be able to recreate the old code (it was years ago, but I still have the script) and make a comment if I end up actually finding statistical anomalies.