Hi!
You can go to: 1) Edit; 2) Players; 3) Create Player; 4) Base Copy (on the bottom); 5) Select the player you want to base copy. The created player will have the same appearance and stats than the original player. Only his "Team role", "Team Role Effect" and "Personality" in Ligue Master will differ in case you might want to have them in a LM (you can't create a Legend by base copying a Legend, ie: Messi). May be its development curve might differ. 6) Add the created player into your team of choice using the transfer in the Edit menu.
I hope this helps!