use warnings;
use strict;

while (my $line = <DATA>){
    my @anchors = $line =~ m#<a name="[^>]+?(?:/>|></a>)#g;
    $line =~ s#<a name="[^>]+?(?:/>|></a>)##g;
    print @anchors,$line;
}

__DATA__
Self: This is an anchor <a name="_Toc00123998" />and these are another<a name="_Toc00123999" /><a name="_Toc00124000" /> couple.
Explicit: This is an anchor <a name="_Toc00123998">no cap</a>and these are another<a name="_Toc00123999"></a><a name="_Toc00124000" /></a>couple.