copying php.ini from another instance

[petr00kos]

if copy php.ini from another instance what happens ?

[Altrea]

The consequence can be that your Apache won't start.
You should never copy the whole php.ini file from anywhere unless you know exactly what you are doing.

The better strategy will be to keep the default php.ini as base and change its configuration step by step (knowing exactly for what the changes are good for).