Just guessing here but I suspect that you are failing to (re-)initialise @FileList between calls? Without seeing the rest of your code it is a bit hard to suggest the best approach but when you first use @FileList you need to initialise it my @FileList=(); and perhaps do so after you have processed the last file @FileList=(); depending on the scope of @FileList.

It looks like you are not using strict, you should do that!

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my $chainsaw = 'Perl';