How? That actually makes no sense.
Thats like saying Kitana is a cheap copy of Jade, or Jade is a cheap copy of Mileena.
Besides having Edenian lineage they have very different and unique stories.
Here's a summary from the wiki for you:
- Jade, Kitana's bodyguard and childhood friend. Though originally loyal to Shao Kahn, Jade has proven her loyalty to the royal family time and again.
- Tanya, who comes from a family of diplomats and ambassadors and used her persuasive powers more than once to betray Edenia to the forces of darkness. She is highly intelligent and skilled in black magic.
They don't even look the same.