I did they are same. As a matter of fact I have copied tnsnames.ora file from the machine test2 where it is working to all locations of tnsnames.ora on oracle816.
Here is the text from sqlnet file. It is also same on both machines.

TRACE_LEVEL_CLIENT = OFF
names.directory_path = (TNSNAMES, HOSTNAME)
names.default_domain = world
name.default_zone = world
automatic_ipc = off

thanks