Royal Krona made all kinds of glass items especially decanter bottles and others for liquors and wines !! I can only tell you what I think may be a possibility !! I think they may be used in a winery or distillery for mixing, blending and testing wines or liquors !! The wine or liquor is drawn from the barrel or container with an item that looks similar to a turkey baster !! Large bulb on one end !! I am sure you know what I mean !! The sample is then inserted through the hole into the bottle !! With the round bottom they can check color by swirling it in the large part, Can check the aroma through the hole because the circular bottle would concentrate the scent !! But then there is the taste test !! Cant pour it out of the hole but with the hole on top use the regular opening to pour it into the glass !! It would likely have a little wire stand to hold it when not in use !! How many do you have ?? Forgot to ask but how big are they ??
I may be so wrong that its laughable but that would be my theory !! If you ever find out what they really are,, come back and tell me !!