Neither for 1.56.0 nor 1.57.0 does the change-log list an update to the random numbers library, so first I am puzzled why the libraries behave differently (though [Math] has undergone some changes -> propagation to [Random]?). Second, it is not clear to me why for the first bunch of uniformly distributed variates the results are identical, while for the second, after normally distributed variates were generated, the are not. It appears that the generation of normally distributed variates changes the whole state of the random numbers engine in a different manner [e.g multiple engine calls ??]. Any insight into what is going on here is much appreciated. And foremost: Is any of 1.55 or 1.57 bugged, that is one should be clearly preferred over the other?
I've observed this, too! The change seems to have been introduced in Boost version 1.56.
Looks like the normal distribution was completely rewritten between those two releases: https://github.com/boostorg/random/commit/f0ec97ba36c05ef00f2d29dcf66094e3f4... Beyond that I know nothing, John.