Double entity of minecart with chest in mineshaft

I encountered a minecart with a chest in a mineshaft and destroyed it with a pickaxe to get all of its contents as usual. Right after destruction I noticed that "another" minecart was still on exactly the same spot, I could also destroy it and therefore had all contents doubled (e.g. an enchanted book with "infinity" in it).

Seed: -867447577459181

/tp -1374 35 1510