Composer dependency and redundancy challenge

Question

I have a complicated Composer dependency challenge.

(1) Imagine a fictional library L, loaded from a Satis repo.

(2) Imagine project A, consisting of various PHP libraries, classes and "application" (primary web) php files.

One of the classes is using library L by require_once() + composer autoload.

Everything fine so far.

(3) Now imagine project B, using library L as well by composer and autoload, but also using parts of project A by require_once() single classes or function files.

Now I have a conflict of two composer autoload functionalities resulting in library L getting loaded two times (with errors, of course)

Do you see any chance for resolving that without having a "inclusion guard" in library L (which I could influence, but do not want to)?

Answer 1

The solution should be not to use require or include anymore, as this leads to the given problems. Why is there any reason to mix this with an autoloader anyways?