  In this note we consider two configurations of twelve lines with nineteen
triple points (i.e., points where three lines meet). Both of them have the same
combinatorial features. In both configurations nine of twelve lines have five
triple points and one double point, and the remaining three lines have four
triple points and three double points. Taking the ideal of the triple points of
these configurations we discover that, quite surprisingly, for one of the
configurations the containment $I^{(3)} \subset I^2$ holds, while for the other
it does not. Hence for ideals of points defined by configurations of lines the
(non)containment of a symbolic power in an ordinary power is not determined
alone by combinatorial features of the arrangement. Moreover, for the
configuration with the non-containment $I^{(3)} \nsubseteq I^2$ we examine its
parameter space, which turns out to be a rational curve, and thus establish the
existence of a rational non-containment configuration of points. Such rational
examples are very rare.
