Something like this is an example of verification (technical term). The question: Was the problem solved right? The answer: if the solutions supplied by two independent softwares are in agreement, the confidence goes up.
Note that this verification is also done (or should have been done) by each software vendor. Abaqus has an extensive verification suite, for instance.
Indeed, and that’s how I found some of the bugs I filed last year when I reported that the Statistics standard library returns incorrect quantiles for floating-point and integer arrays.
It’s also how I noticed that some of Julia’s functions for floating-point division return the wrong answer – the one that’s supposed to return the floor (fld) sometimes returns the ceiling, and the one that’s supposed to return the ceiling (cld) sometimes returns the floor.
There’s often a burst of attention after a serious-looking issue gets filed or when a link is posted in a particularly visible place.