why I can’t run a program with the same name in another terminal? (C progra

I have a really big problem because I have to call the file with the same name twice and I have this error all the time:

ELF binary type "0" not known.
-bash: ./a.out: cannot execute binary file: Exec format error

https://pastebin.pl/view/6dd51419

I have to write a game for two people like udp so that they are logged in on different machines, and I can't even run a program with the same name in a different terminal ...