He may have been nicknamed after the former Scotland striker, to whom he bears a passing physical resemblance. The back of his Brondby shirt may have been adorned with the moniker 'Duncan' for the past four years. But as he completed his 1.5million move to Celtic yesterday, the Danish international front man was at great pains to lay any comparisons with big Dunc to rest. Celtic supporters, of course, were never going to embrace the label in any case and there was no prospect of Rasmussen's new hooped No19 shirt bearing the name of the former Rangers player.
"It was a nothing comparison, I don't even know why they called me that now, it was so many years ago," said Rasmussen. "I think he (Ferguson] was playing for Everton at the time and the coach who gave me the nickname was friends with Claus Thomsen who used to play with him at Everton. They must have thought I was a little crazy, so they gave me that name. I don't know. People started to call me Duncan when I was at Aarhus, but it was only when I moved to Brondby in 2006 that they thought it was funny to maybe sell some more shirts by putting that name on my shirt.
"That was okay, but I like my own name and now I want it back on my shirt. Actually, Ferguson wasn't even a player I liked or modelled myself on. I don't think I even knew much about him when I first got the nickname.
"It doesn't really matter. In Denmark, when they talk about Duncan now, they think of me rather than Duncan Ferguson."
It was clearly not a matter of levity as far as Rasmussen was concerned when he was unveiled at Lennoxtown yesterday. This is a player with something of a troubled past, including a gambling addiction, he does not wish to discuss. He will celebrate his 25th birthday this weekend and hopes his move to Celtic, where he has signed a three-and-a-half year contract, signals a fresh chapter in his life.
"I'm older now and moving to a big club like Celtic is a new chance for me to grow up," he said.
"Some things happened to me in the past and I don't actually want to talk about those things anymore. Those are old stories now, I want to look forward."
So if his advance publicity had indeed been misleading, what can Celtic supporters expect from Rasmussen?
"I'm what they call an old-fashioned striker," he says. "I like to keep it simple and get into the box as fast as possible, fight for the ball and hopefully score some goals."
An impressive ratio of 72 goals in 187 Danish Super League appearances for Aarhus and Brondby since making his senior debut in 2002 helped Rasmussen represent his country at every level. He now has three full caps and is in contention for a place in Denmark coach Morten Olsen's squad for the World Cup finals in South Africa this summer.
Rasmussen hopes his move to Celtic can assist him on that front, although he admits he is at odds with Olsen's view of the relative merits of the Danish Super League and the SPL.
"He (Olsen] said he thought the Danish league was better," said Rasmussen, "but, of course, Celtic and Rangers are better than any Danish clubs. From what I have seen, the Scottish game is more physical and has a higher tempo, so I think it is better.
"I hope this will be a big thing for me to help me to go to the World Cup. I will do the best I can for the rest of the season here and fight for it."
Rasmussen has experienced a frenetic few days, travelling back from helping a Danish League squad win the King's Cup tournament in Thailand at the weekend for a brief stopover in Copenhagen before heading to Scotland to pass a medical and complete his move to Celtic. He has declared himself fit and ready to make his debut against Hibs at Celtic Park tonight.
"I played two matches in the last week for the national squad in Thailand, so I think I am fit enough to play," he said.
"It has been a little crazy, but it's such a big thing for me to join Celtic. I came here a few years ago, when I was a kid at Aarhus, with Marc Rieper to train with the Celtic youngsters. I went to watch a game at Celtic Park and I remember the atmosphere was fantastic. It's really a dream for me to now get the chance to play at a big club."