I stumbled on the same.
It is indeed a display thing. If you check the "Normal", the underlying value appears:
Normal[data100]
Equal@@@Map[IntegerPart,Normal[data100],{2}]
{<|"Int" -> 499376, "Real" -> 499376.|>, <|"Int" -> 496899, "Real" -> 496899.|>, <|"Int" -> 491584,
"Real" -> 491584.|>, <|"Int" -> 494629,
"Real" -> 494629.|>, <|"Int" -> 490165, "Real" -> 490165.|>}
{True, True, True, True, True}