Not necessarily. These could have been made up on cases left over from in-factory test firing, or simply reclaimed brass. Doesn’t mean the weren’t factory made into dummies. Then again, of course, it doesn’t mean they were.
In this instance, I would take Hammer’s word on the subject. He is very expert on Finnish ammunition, or at least that is my own observation from looking at this Forum from its beginning.
You should see the assortment of headstamps I have on Swedish 9mm rounds that used any old brass - dummies, blanks, gallery loads. The same for Danish. German, Finnish, English, Swedish, military, civilian, contract, etc.