What happens if I buy another Batman only for the dlc? Help .. :)

[[ARG] Sleepy]

What happens if I buy another Batman only for the dlc? Since Amazon is the Goty version and as I live in South America I can only get this game if I give it away or putting a key to another region. What would happen with my other Batman Arhkam City? It may or tell me that I have one and would not let me have another?

Google Translate ... sorry if no is good write

[[ARG] Sleepy]

oh thanks