It seems that when a label is changed, the value isn't always updated cleanly in the Blazegraph database, which will sometimes return both the old label and the new label.
For example,
PREFIX wd: <http://www.wikidata.org/entity/>
SELECT ?p ?lang ?o WHERE {
wd:Q1006876 ?p ?o .
BIND (lang(?o) AS ?lang)
}Here for Q1006876 there are three 'en'-language labels returned, "UK borough", "borough in the UK", and "borough in the United Kingdom", when there should only be the latter. This has now been the case for a number of weeks.
Similarly, Q21497886 (label edited this evening) is now also showing two en-language labels