Created attachment 29525 [details] jpg and programe 20 rows , half of them is cover 59secend to 58
The XLSX contains two slightly different native values for the timestamps: The first 9 rows contain 41224.999988425923, the others 41224.999988368058, it seems POI computes a slightly different time for the second value.
There is now a reproducer-test in TestUnifxedbugs for this Bug.
I could get this to lead to equal dates by setting the parameter "roundSeconds" in DateUtils.getJavaDate() to "true", however there might be some side-effects so I am not sure if this is really the correct fix here as many other places still would call it with "false" via other code-pathes. We probably should decide if we should do this rounding always without the additional parameter to avoid the error-prone different handling of this conversion.
As stated in #56269 I'm +1 for using the rounding as the default.