See https://www.wikidata.org/w/index.php?title=Q474157&diff=200753230&oldid=200706473
The label "collaborative software" already existed in the target, but an alias "Collaborative software" was added.
This should perhaps not be the case and instead don't add the alias...
I believe the change is / needs to be at https://github.com/wikimedia/mediawiki-extensions-Wikibase/blob/master/repo/includes/ChangeOp/ChangeOpsMerge.php#L168
where we currently have the following but instead need a case insensitive check:
$toLabel === $label