User blog comment:Belle pullman/Cast List References/@comment-3182821-20190922145007/@comment-39097528-20190922150436

The Book that I took the info from gives those names as being in the cast in 12/99, leaving and then rejoining the cast later in 2000. It could be that several cast members went on vacation around the Christmas period and those 12/99 cast members were their temporary covers, before they joined permanently months later.