I have have only reproduced issue on 1 card configuration.
Epg grabber sequence could start between tuning to scheduled channel and starting recording.

Bug thread on public forums with test binary:
http://forum.team-mediaportal.com/mediaportal-1-1-0-rc-3-519/failed-record-all-scheduled-program-82575/

h4. Steps to Reproduce
1. Leave one card enabled
2. Schedule a recording
3. Hit refresh dvb epg in tvsetup to force it
4. wait for scheduled recording begins
Check your logs