Swedish King's Tomb Misidentified

I find this a very interesting article for its implications.  What other mistakes have been made based on the assumption that those who came before us had it right?

Wrong persons found in King´s tomb
Culture | 2011-12-09

King Magnus Ladulas

The Swedish King Magnus Ladulås (1240-1290 a.d.) is buried in the Riddarholmen church (Riddarholmskyrkan) in Gamla Stan, Stockholm. This is at least what everybody have taken for granted...until new facts were presented recently. A new radiocarbon dating of the tomb's content indicates that the content of the tomb comes from the remains of nine persons who were buried some time between 1430 and 1520, i.e. at least 200 years after King Magnus.

It is thus clear now that King Johan II (son of Gustav Vasa) put up the pompous tomb above the wrong grave. The research group around Magnus Ladulås tomb is very excited about their new discovery and want to open a nearby tomb. They write the following on their blog:

"It is a fantastic story that is rolled up in front of our eyes. Johan II had the impressive tomb put up above the wrong grave and this historical hoax has been unchallenged for 400 years! On good grounds we believe instead that Magnus Ladulås was placed in the southern tomb in front of the choir, i.e. the tomb in which King Karl Knutsson placed himself in the 15th century. With the knowledge we have today it is obvious that we have only done half the job. In order to make further progress in this project we need to open also the southern part of the choir-tombs (the tomb of Karl Knutsson) and investigate all individuals there." (Stockholm News translation.)

If the research group's application to open this tomb is accepted by the Royal court of Sweden, it can start in 2014 at the earliest.

Short background about King Magnus Ladulås:

King Magnus Ladulås was the first 'Magnus' to rule Sweden for any length of time. He was king of Sweden 1275-1290.

The name 'Ladulås' is thought to come from his decree of 1279 prohibiting travelling nobles or bishops to demand from the peasant to provide them with food and beds. The word Ladulås is therefore believed to be the name he got after this decree.

Ladulås means "the lock of the barn", i.e. the right of the peasants in Sweden to say no to travelling nobles of enterring their house. Another theory of the name 'Ladulås' is that it refers to his Slavic heritage and would in that case be 'Ladislaus'.