if (scalar @titles > scalar %titles) {   # no, some basenames are non-unique

##</code><code>##

$ perl -le'
my @x = "a" .. "z";                                           
$x{ $_ }++ for @x;
print for scalar @x, 0 + @x, scalar %x, 0 + %x;
'
26
26
19/32
19


##</code><code>##

   if ( @titles > keys %titles ) {   # no, some basenames are non-unique