For a year now, people have been pouring data in to Wikidata and, there is a lot of it. This data is coming from many places; among them all the Wikipedias. They do not necessarily agree on everything.
One area where it particularly makes sense to cooperate are the recently departed. Many of the people who were notable enough for an article are old and, they die. They die in droves.
As some people are described in several languages, you may find that those other Wikipedians knew about it first. So you may learn about even more deaths in the ranks. Another thing that happens is that people enter a different data... OOPS...
This is where you keep calm and cite your sources. People only die once, so this is the time to be assertive about your sources.
Wikidata is at this time happy when you sort it out, get it right and update its data accordingly. Adding sources is really appreciated but at this time we are mostly happy when you concur that we have the same data.