Did I imagine this or in the early days of DOI did they do a Christmas show one year before the series started?

http://www.youtube.com/watch?v=yUjwLbIHCCU

Dec 25th 2008 - Jayne Torvill and Christopher Dean are pitted against each other, as they train two teams of Dancing On Ice stars.''''Team Torvill will be actresses Clare Buckfield, Suzanne Shaw and Zaraah Abrahams and their skating partners.''''Team Dean is an all-male affair with actor Chris Fountain, Blue singer Duncan James and rugby player Kyran Bracken plus their professional counterparts.''''Catty judges Jason Gardiner, Robin Cousins, Ruthie Henshall and Nicky Slater will decide who wins.

Thanks for that I wonder why they have never repeated it?

Probably because Chris got injured during the Christmas show and then wasn't able to skate for the first few weeks of the series that started just after. With Strictly, the Christmas show comes at the end of the series and involves eliminated pros. With DOI the Christmas show would be right before the start of the series and they most likely don't want to risk Chris, Jayne or any of the pros getting injured just before the series starts. Although given that Sylvain just got injured during pre-show training, I'm not sure how much weight that theory carries.