I've seen this a few times now but it doesn't appear to do it all the time. To reproduce:

1. Add 2 custom attributes to a survey and the same 2 to the CPD
2. Add participants (I imported from LDAP) with custom attributes
3. Tick 'Select all' checkbox to select 25 participants
4. click 'Add Participants to Central Database' button
5. Map the attributes from the survey to the CPD
6. Click Continue
7. Note the error below.
8. The participants appear to be added as required
9. Delete the participants and then start from step 3
10. Note at step 5 that one attribute is pre-mapped, the other is not
11. Error appears again, next time both attributes are pre-mapped and no error.

NB: The pre-mapped attributes don't have friendly names ie 'attribute_cpdb_2'

NB I Also get a minor JS error on the mapping screen (but I always get this):

TypeError: $(this).qtip is not a function
[Break On This Error]
hide: {when: 'mouseout'}

<h1>PHP Error [2048]</h1>

Non-static method ParticipantAttributeNames::getAttributeNames() should not be called statically, assuming $this from incompatible context (C:\limesurvey_test\application\models\Participants.php:1265)

#0 C:\limesurvey_test\application\models\Participants.php(1265): LSYii_Application->handleError()

#1 C:\limesurvey_test\application\controllers\admin\participantsaction.php(1735): Participants->copyToCentral()

#2 unknown(0): participantsaction->addToCentral()

#3 C:\limesurvey_test\framework\web\actions\CAction.php(107): ReflectionMethod->invokeArgs()

#4 C:\limesurvey_test\application\core\Survey_Common_Action.php(82): participantsaction->runWithParamsInternal()

#5 C:\limesurvey_test\framework\web\CController.php(309): participantsaction->runWithParams()

#6 C:\limesurvey_test\framework\web\CController.php(287): AdminController->runAction()

#7 C:\limesurvey_test\framework\web\CController.php(266): AdminController->runActionWithFilters()

#8 C:\limesurvey_test\application\controllers\AdminController.php(159): AdminController->run()

#9 C:\limesurvey_test\framework\web\CWebApplication.php(276): AdminController->run()

#10 C:\limesurvey_test\framework\web\CWebApplication.php(135): LSYii_Application->runController()

#11 C:\limesurvey_test\framework\base\CApplication.php(162): LSYii_Application->processRequest()

#12 C:\limesurvey_test\index.php(178): LSYii_Application->run()