We’ve uncovered a little version-ing featurette in SharePoint 2007
When you copy a document from one document library to the other using K2 [blackpearl] or using standard SharePoint code, you’ll find that the previous versions of the document are not present in the new location.
Jason Apergis found this out back in 2007 and published a neat little work-around: here
Excellent stuff…. a colleague of mine, has also published his ideas on a workaround to this issue: here. I just can’t believe Microsoft let this one exist in the final product 
SpittingCAML