Ok so I have 4.2 installed and I have the same problem... fresh Ubuntu 12.10 64bit install...
When I move, delete, or change anything in iCal I have to do every twice before it will stick...
OK… LOGS… I'm using iCal 5.0.3 and 4.0.4 both the same issues
In iCal I create a event at 3:00pm March 6 and it seems to be ok…
2013-03-06 14:47:07-0500 [-] [caldav-0] [HTTPChannel,17,24.201.74.72] [twext.web2.server#info] PUT /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
2013-03-06 14:47:07-0500 [-] [caldav-0] [HTTPChannel,18,24.201.74.72] [twext.web2.server#info] PUT /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Updating group membership cache
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Group membership snapshot file exists: /var/lib/caldavd/memberships_cache
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Attempting to acquire group membership cache lock
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Acquired lock
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Retrieving list of all proxies
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] There are 0 proxies
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Retrieving group hierarchy from directory
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] 1 groups retrieved from the directory
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] 0 groups are proxies
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] There are 0 users delegated-to via groups
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Taking snapshot of group memberships to /var/lib/caldavd/memberships_cache
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Storing 0 group memberships in memcached
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Releasing lock
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Group memberships cache updated
2013-03-06 14:47:18-0500 [-] [groupcacher] 2013-03-06 14:47:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacherService#info] Scheduling next group membership update
Then I move the event to 4:00 … and it jumps back to 3:00
2013-03-06 14:51:02-0500 [-] [caldav-0] [HTTPChannel,19,24.201.74.72] [twext.web2.server#info] PUT /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
2013-03-06 14:51:02-0500 [-] [caldav-0] [HTTPChannel,19,24.201.74.72] [twext.web2.server#info] GET /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
2013-03-06 14:51:02-0500 [-] [caldav-0] [HTTPChannel,20,24.201.74.72] [twext.web2.server#info] GET /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
Then I move the event to 4:00 again … and it stays at 4:00
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Updating group membership cache
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Group membership snapshot file exists: /var/lib/caldavd/memberships_cache
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Attempting to acquire group membership cache lock
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Acquired lock
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Retrieving list of all proxies
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] There are 0 proxies
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Retrieving group hierarchy from directory
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] 1 groups retrieved from the directory
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] 0 groups are proxies
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] There are 0 users delegated-to via groups
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Taking snapshot of group memberships to /var/lib/caldavd/memberships_cache
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [-] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Storing 0 group memberships in memcached
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Releasing lock
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacheUpdater#info] Group memberships cache updated
2013-03-06 14:52:18-0500 [-] [groupcacher] 2013-03-06 14:52:18-0500 [PooledMemCacheProtocol,client] [twistedcaldav.directory.directory.GroupMembershipCacherService#info] Scheduling next group membership update
2013-03-06 14:52:20-0500 [-] [caldav-0] [HTTPChannel,21,24.201.74.72] [twext.web2.server#info] PUT /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
2013-03-06 14:52:20-0500 [-] [caldav-0] [HTTPChannel,22,24.201.74.72] [twext.web2.server#info] PUT /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
Then I delete the event at 4:00 but it come right back
2013-03-06 14:53:31-0500 [-] [caldav-0] [HTTPChannel,23,24.201.74.72] [twext.web2.server#info] DELETE /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
2013-03-06 14:53:31-0500 [-] [caldav-0] [HTTPChannel,23,24.201.74.72] [twext.web2.server#info] GET /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
2013-03-06 14:53:31-0500 [-] [caldav-0] [HTTPChannel,24,24.201.74.72] [twext.web2.server#info] GET /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
Then I delete the event at 4:00 again and this time it is gone
2013-03-06 14:55:01-0500 [-] [caldav-0] [HTTPChannel,25,24.201.74.72] [twext.web2.server#info] DELETE /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
2013-03-06 14:55:01-0500 [-] [caldav-0] [HTTPChannel,26,24.201.74.72] [twext.web2.server#info] DELETE /calendars/__uids__/1cc63f8f-744a-4941-88c8-8ab121d03be9/calendar/D49F6977-1BCA-4EB3-A602-510B2037DC81.ics HTTP/1.1
It seems to me the Following GET operations are reading back the old data?