I thought the following information might be useful here, since you are perfectly right that Kuttrolf decanters are not
synonimous with Holmegaard.
McConnell writes this about them in his book The Decanter An Illustrated History of Glass from 1650
, on page 151:
"The date of the earliest Kuttrolf
is unknown, but multi-necked vessels were made in Syria and Roman Gaul c 400-500. A twist-necked version [no stopper, but wide neck] is illustrated in a 15th century woodcut (plate 214), and a young man is seen drinking from another in van Ratgeb's painting The Last Supper
, c1510. The Kuttrolf
continued in production throughout the 17th and 18th centuries and enjoyed a popular revival between c1890 and 1930."
On page 416 he goes on to illustrate a number of Kuttrolfs, including three line drawings of Holmegaard and another of a Kastrup, dating from 1923 to 1930. As we know they also produced them in the 1960's and 1970's.
Looking at your one, it seems that the stopper has a different mould pattern to its surface, which concerns me, since I would have expected the stopper to reflect the base. Interestingly the problem occurs on the one shown on the link.
This brings me to a discussion about what I perceive to be to common problem, the swopping and replacement of stoppers on decanters. It is not always easy to tell when this has occurred, but one indication is usually when the base and top don't match, however well they might fit. After all it is easy enough to find a reasonable, or approximate, match and have it ground in - provided that the peg is large enough. Further is is perfectly easy to inscribe a number to the stopper to match that of the body (should there be one).
Of course this can happen within the history of the piece, since stoppers do get lost or misplaced by owners (often when moving) so a replacement might be many years old. However it happens it will effect the commercial value of a piece - but not necessarily its enjoyment.