To be more precise: the guarantee is per person, per bank license holder.
In the case of bunq that does not make any difference, but when you have finds at Knab and Aegon for example, you are dealing with one and the same licence holder. Same goes for Abn-Amro and MoneyYou (or whatever that branche of theirs is named).
Also be aware that money in a joined account has to belong to both of you when one person owns the money and the other jus has access to it, only the funds of the owner are covered by the guarantee up to the limit.