Then these are definitely two different events! A recurring event is one that occurs multiple times. Certainly, they may vary in the start or end time, but if they are repetitions of the same event, then they should have some commonality.
No, this is an error UNLESS the semantics are that when this occurs, it is a short-hand for "take the time portion of the date/time" from the original DTSTART and DTEND. This makes sense to me. For example, define a -T080000Z to -T090000Z meeting (a soiree for us US-Eastern time zone folks ;-) ) event that is augmented with a RDATE property that specifies 5 other dates. The interpretation is that these 5 other occurrences are at the same start/end as the first occurrence.
Other wise, there appears to be a value type mismatching here also introduces this hybrid event that is both a traditional appointment and a day-long event. Too weird.