Some decanters were signed in the early-mid 1950s with just the Lutken monogram and a date - but they're few and far between in number - and select tableware (decanters and glasses) was initialled 'HG' followed by a number during 1971-85. Never found any fully signed glasses before this date, though. Even so, the glasses in the auction are only signed 'PL' - on it's own, it's not a known HG signature. The Aristocrat decanter from the same seller apparently has a monogram and a date (1958)... I've had several Aristocrat decanters, but never with a signature - not even a limited edition 1958 silver-mounted one I own. And I've certainly never heard of a signature on a stopper!
In any case, the signatures don't seem to match the known Lutken monogram, judging by the seller's caginess when I asked if they matched the example of a Lutken monogram on my site. Instead he just said that there was bound to be variation in signatures and colouring during Lutken's tenure at Holmegaard.