HOE registered theirs with the Scottish Tartans Authority in 1995. They just picked colors and designed tartans that they liked.

The County Crest tartans were created in 2005 and are NOT registered with the STA, although they are copyrighted in the UK. They took the colors from each of the county's crests and created tartans based on those colors.

NEITHER are officially recognized, but due to the fact that the HOE ones have been around since 1995, they're more recognized by the "general public".