I'm just wondering why you didn't get Can't localize lexical variable %s instead?   But it looks like that is because you have more than one %opts variable in your program.

Anyway, local only works on package variables and hides the value(s) of that variable in the current scope.

You should probably have a look at Coping with Scoping for more details.

Update:   Also put these two lines at the beginning of your program:

use warnings;
use strict;
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