RSS feed output correct but import 1 day before

i tested different RSS import plugins to show events on other external pages.
on the feed itself the dates are correct.
But if i have “ganzt?gig” : full-time events ( from 0:00 to 24:00) the import on the external page shows the date 1 day before the correct date.
Is there a way to avoid it without editing all full-time events to timed events.
Or is there a possibility to change the time-range of full-time events to 0:01 to 24:00. Guess that will do the job too. Or do you have a solution for that.
Thanks in advance.