Friend must grab horse with carcass once it comes out the stable fast otherwise you wont get the dupe, also this glitch is highly unstable and sometimes doesnt even work. Small update removed legendary from title they work, just put 5 into hunting wagon and donate to Gus.
Requirements:
Friend...
LOBBY SENSITIVE
REQUIREMENTS
1. HAVE A HORSE
2. HAVE A ANIMAL (COUGAR, PANTHER, ETC.) 3 STAR
STEPS
1. PUT THE ANIMAL ON THE HORSE
2. TELL YOUR HORSE TO FLEE AND THEN STAY
3. THE ANIMAL SHOULD DISAPPEAR
4. CALL YOUR HORSE BACK (IT SHOULD STILL HAVE AN ANIMAL ON ITS BACK)
5. TELL YOUR HORSE TO...
I stumbled across this video on YouTube. He manages to dupe a Lake Sturgeon he placed on the ground, while there's one on his horse. Haven't gotten a chance to mess around with this yet but it looks interesting to say the the least.