[ObjectMetadata]

Hi Dolgubon, thanks for your reply!
I checked what you said but the parameter "containingControl" is passed as a hard reference, so it should definitely be the same both times.

This is the function I use to call the "CreateQuestLabel" function:

function TestAddon:AddQuestsToGrid()
    local noOfQuests = GetNumJournalQuests()
    local yOffset = 50
    for i = 1, noOfQuests do
        local labelName = "QuestLabel" .. i
        local checkboxName = "QuestCheckBox" .. i
        local label = self:CreateQuestLabel(i, labelName, TestAddonGrid, yOffset)
            --TestAddonGrid is the TopLevelControl in the .xml file
        local checkbox = self:CreateQuestCheckBox(i, checkboxName, TestAddonGrid, label)
        yOffset = yOffset + 50
    end
end

XML-Code:

<GuiXml>
	<Controls>
		<TopLevelControl name="TestAddonGrid" mouseEnabled="true" movable="false" clampedToScreen="true" hidden="true">
			<Controls>
				<some controls />
			</Controls>
		</TopLevelControl>
	</Controls>
</GuiXml>

The AddQuestsToGrid function gets called by a slash command.
type slash command for the first time -> everything workes as intended since the controls don't yet exist
type slash command for the 2nd time -> Duplicate error

Could this be caused by some weird object instance behaviour? Like that the object "TestAddonGrid" is not the same instance the second time as the first time?