How to move only files with other equal filename but differe

#!/bin/bash

todir=$1

cd $( dirname $0 )
DIRLIST=$( ls -F | grep '/' | tr -d '/' )

for DIR in $DIRLIST
do
    mp3num=$( ls $DIR | grep -c \\.mp3 )
    m4anum=$( ls $DIR | grep -c \\.m4a )
    filnum=$( ls $DIR | wc -l )

    echo $DIR $mp3num $mp4num $filnum

    if [ $DIR = $todir ]; then
        continue
    fi

    if [ $m4anum = 0 -o $mp3num = 0 ]
    then
        continue
    elif [ $mp3num != 0 -a $m4anum != 0 ]
    then
        mv $DIR/*.mp3 $todir
    fi
done