Complex sentence: The WB and UPN followed the "common prime" scheduling model when they both launched in January 1995; the replacements for those networks, The CW and the MyNetworkTV program service, similarly utilized that model upon their launches in September 2006.
Split into simpler sentences: The WB and UPN followed the "common prime" scheduling model when they both launched in January 1995. All of that were replaced by The CW and the MyNetworkTV program service upon their launches in September 2006.