ngg_prev_symbol filter on $next_symbol

I was on my way to filtering the next and previous arrows from the ◄ and ► symbols when I noticed the filter for the variables $prev_symbol and &next_symbol had the same filter hook – ngg_prev_symbol.

Shouldn’t the filter for $next_symbol be something along the lines of ngg_next_symbol because I can’t really change them both separately with filters as far as my limited knowledge of filters goes.

$prev_symbol = apply_filters( 'ngg_prev_symbol', '&#9668' );
$next_symbol = apply_filters( 'ngg_next_symbol', '&#9658' );

I’m using NextGEN Gallery 1.9.13

https://www.ads-software.com/extend/plugins/nextgen-gallery/