Concatenate files with different mc infos
When concatenating two files that have differnt recarray columns, the first file that is given will determine the columns in the output file. All other columns of files afterwards wont get their columns added. E.g. File 1: Columns in "y": run_id File 2: Columns in "y": run_id, energy
Concatenated file: Columns in "y": run_id (energy does not appear)