The EPG in Mediaportal is build for single line program titles.

According to this report there is a provider which does supply multiline titles, and it also shows the result:

http://forum.team-mediaportal.com/submit-code-patches-mediaportal-tv-server-etc-325/mantis-0002874-multiline-channel-titles-display-correctly-guides-info-windows-76968/

According to that thread, and also in tontsa, chemelli and my opinion the new lines and tabs should be removed on import.

Removing double spaces as suggested in the thread does not seem a good idea, but you have to be careful about spaces when removing the newline characters.

h4. Steps to Reproduce
Import WebEPG xml containing new line characters in the program title field.