The first address - given the theme "just be yourself" - will see diversity programme stars Max Laird from Seven Dwarves, Susan Campbell-Duncan of Beauty And The Beast, My Transsexual Summer's Karen Gayle and acid attack victim Katie Piper from Katie: My Beautiful Friends make a "plea for tolerance".
The second will be fronted by Educating Essex headmaster Vic Goddard and his deputy Stephen Drew.
It is the first time since the annual broadcast began in 1993 that viewers will see multiple messages.
"Channel 4's Alternative Christmas Message is a yuletide institution giving voice to different opinions and social attitudes," director of creative diversity Stuart Cosgrove told The Guardian.
"This year the [first] message is collectively authored by people who have all starred in shows which foreground diversity. The message is a plea for tolerance and praises difference in a society that often demands conformity."
Previous stars of the channel's Alternative Christmas Message have included Jamie Oliver, Iranian president Mahmoud Ahmadinejad, a 9/11 survivor and The Simpsons.
The 2010 message was delivered by midwives and medical staff being filmed for One Born Every Minute, while Piper made a first appearance the previous year.
'Just Be Yourself' will air on Christmas Day at 1.55pm on Channel 4, followed by the Educating Essex Christmas message at 4.15pm the same day.