This is a misconception.
If we follow DMM then...
1. A 6* winning 1st place will be a completely new 6* unit with different stats, skill and abilities than the original.
*That means that if Black Baccara wins, then we will get 2 Black Baccara's (Original 6* and the new 6*unit) in the game.
2. A 6* winning 2-3rd place will be a completely new 5* unit with different stats, skill and abilities than the original.
*That means that if Black Baccara wins 2nd/3rd place, then we will get 2 Black Baccara's (Original 6* and the new 5*unit) in the game.
3. A winning 5* unit will have the same treatment as above.