How to distinguish one module from another?

Question

PHP

There are 2 open source modules, there is a server. The modules send requests from the client side to our server, with different parameters, the response from the server is approximately the same (some data is different, but they do not greatly affect the result). If you redirect the second module to the handler of the first one (the handler on the server side), then it will work, but not quite correctly. How it is possible to be protected from such redirection? The client has a code, it cannot be trusted, but how on the server side to understand what's what, because the code can be modified.

Answer 1

Authenticate on the server

Answer 2

In general, no way.
There are options:
1) Close the code from the client, for example Zend Encoder / Zend SafeGuard Suite
2) Make a self-signing code, I did not find any examples. The bottom line is that the script itself contains an identifier / hash, and when sending data, they are signed with a key generated based on the source code of the script, so modifying the code will corrupt the key and the transmitted data.