remove-duplicates: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/remove-duplicates - from package: recoverjpeg

You may install the required package with command apt-get install {package}

Error in other languages:
remove-duplicates: bevel nie gevind nie
remove-duplicates: comandă negăsită
remove-duplicates: comando não encontrado
remove-duplicates: commande introuvable
remove-duplicates: command not found
remove-duplicates: käsku ei ole
remove-duplicates: không tìm thấy lệnh
remove-duplicates: komanda nerasta
remove-duplicates: Kommando nicht gefunden.
remove-duplicates: kommandot finns inte
remove-duplicates: komut yok
remove-duplicates: nie znaleziono polecenia
remove-duplicates: níor aimsíodh an t-ordú
remove-duplicates: no se encontró la orden
remove-duplicates: no s'ha trobat l'ordre
remove-duplicates: opdracht niet gevonden
remove-duplicates: parancs nem található
remove-duplicates: perintah tidak ditemukan
remove-duplicates: príkaz nenájdený
remove-duplicates: příkaz nenalezen
remove-duplicates: команда не найдена
remove-duplicates: командата не е открита
remove-duplicates: 命令找不到
remove-duplicates: コマンドが見つかりません