You cannot eval completion scripts for multiple binaries.

[lkarbownik]

When you try to eval two different completion scripts for two different binaries only the last one is working correctly.

e.g.
Evalutuating the folowing code will result in completion working properly only for the binary2

eval "$(binary1 --completion-script-zsh)"
eval "$(binary2 --completion-script-zsh)"

The issue seems to be caused by running compinit again, which resets completion module and removes previously added autocompletion scripts.

I propose to remove calls to compinit and bashcompinit and leave this responsibility to the user.

[lkarbownik]

Temporary solution for those of you who encountered this problem.
You can use the following snippet to evaluate multiple completion scripts correctly in .zshrc:

eval "$(binary1 --completion-script-zsh | sed '/^#/d;  /^autoload/d')"
eval "$(binary2 --completion-script-zsh | sed '/^#/d;  /^autoload/d')"