Another example:
Just add another substitution foreach case...

use strict;

while(<DATA>){

~s/copyright\s+(\d+)-(\d+),\s+(\d+)/copyright $1-$3/i;

print;

}

__DATA__
Given a string like "copyright 1990-2000, 2001. All rights reserved ..
+.


OUTPUT:
Given a string like "copyright 1990-2001. All rights reserved ...
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JamesNC