First of all, any already saved match will still have by default the 0:0 score, that you’ll need to delete by yourself.
Then because there’s a bug in the matches results’s update function when it’s not filtered you have to filter by day to update your result.
To get rid of the first problem (default 0:0) in the new added matches open your ..//wp-content/plugins/leaguemanager/admin/matches.php
find
<input class="points" type="text" size="2" style="text-align: center;" id="home_points_<?php echo $match->id ?>_regular" name="home_points[<?php echo $match->id ?>]" value="<?php echo (isset($match->home_points) ? $match->home_points : 0) ?>" /> : <input class="points" type="text" size="2" style="text-align: center;" id="away_points[<?php echo $match->id ?>]" name="away_points[<?php echo $match->id ?>]" value="<?php echo (isset($match->away_points) ? $match->away_points : 0) ?>" />
and replace with
<input class="points" type="text" size="2" style="text-align: center;" id="home_points_<?php echo $match->id ?>_regular" name="home_points[<?php echo $match->id ?>]" value="<?php echo (isset($match->home_points) ? $match->home_points : null) ?>" /> : <input class="points" type="text" size="2" style="text-align: center;" id="away_points[<?php echo $match->id ?>]" name="away_points[<?php echo $match->id ?>]" value="<?php echo (isset($match->away_points) ? $match->away_points : null) ?>" />