I fail to see the benefit for anyone to simultaneously make a hold of 1USD and a purchase of 600DKK.
Finnair never did this before. They made a hold of the actual amount and if it didn't clear, they didn't issue the ticket. I know, because it has happened to me that other transactions took precedence and when Finnair tried to process money, I was over limit. In these cases, they would contact me and let me know that if payment wasn't processed within 24h the reservation would be released.