✓ Accepted answer
First of all, please refrain from asking questions of "asking to make scripts" -- those aren't allowed here!
But all that aside it just depends on how Roblox handles it. They might have a system in place that prevents this from happening but I am not 100% sure.
Aside from that you can't really check if a player is actually who they say they are (unless you decide to create a very complex system yourself that uses other methods outside of the Roblox API) other than just having to trust the ":FireServer" function to give you the actual player.
They can fire all ":FireServer" events that are available to everyone so keep that in mind when making your scripts and to NEVER allow to have a "RemoteFunction" or "RemoteEvent" that just fires to allow control of things without any security checks within Scripts (also NEVER run those checks in LocalScripts because you want the server to check and not a player's client).
If you have any questions or issues contact me. ;)
2 comments
The first argument is aways the player on that type of events
I know, but inside a localscript u write "FireServer()" and the server receive the player name "local function example(player)" but... they can fire the server for another guy inside the server?