Dual citizenship means a totally different thing speaking of Swedish-Finnish or, for example, Swedish-Turkish dual citizens.
This is due to the fact that between Nordic countries, official information exchange simply works really well. When a Nordic citizen registers in some other Nordic country, they can only take advantage of social security in the country they are living in.
For example a person who lives and is registered in Sweden. When they enter Finland, they will not be able to lift unemployment or social benefits unless they are registered in Finland. When a person moves registration from Sweden to Finland, this will be visible in the Swedish registry office in a couple of weeks, even if the person does not inform authorities about their moving out. The Finnish registry office confirms Sweden’s equivalent office about the registration. The same practice is in use between all Nordic countries.
This co-operation between authoritatives makes sure that cannot be registered in two or more countries and lift social benefits in each of them.
The situation changes totally when it is a dual citizen of, let’s say Turkey and Sweden. If this person moves to their home country, Turkey, without informing it to authorities, they can still lift unemployment benefits from Sweden. There is no official exchange of information between Turkey an Sweden, so it is possible for this person to live and work in Turkey, at the same time lifting some extra disco money provided by Swedish taxpayers. A few times a year, they may have to fly to Sweden to participate in a meeting with the unemployment office, to keep the benefits coming. Other than this, all reporting happens on the internet.
A family with just a few children gets child benefits by an amount per month that lets them live quite comfortably in Turkey. The family were to inform the authorities about their moving out, they would get no more child benefits. A similar kind of move from Sweden to Finland would just mean that Finland would pay the benefits instead.
This is one reason to question dual citizenship involving faraway countries.
During the recent elections in Sweden, it was noticed that thousands of Turkish-Swedish dual citizens cast their votes in Turkey.