I've been looking at commercial madras curry powder ingredients and how they vary across the brands.
Here is just a few.

KTC Mild Madras Curry Powder

Ingredients: Coriander, Cumin, Chanadall, Turmeric, Fennel, Paprika, Red Chillies, Fenugreek, Mustard, Rock Salt, Black Pepper, Ginger and other spices.
MDH Madras Curry Powder

Ingredients:
Coriander, Chillies, Cumin, Turmeric, Fenugreek Leaves, Salt, Black Pepper, Dry Ginger, Mustard, Bay Leaf, Pulse, Cloves, Nutmeg, Caraway, Cinnamon, Cardamom Seeds, Mace, Asafoetida.
Indus Madras Curry Powder

Ingredients
Coriander,Turmeric ,Mustard ,Bengal Gram Farina ,Cumin ,Chillies ,Fenugreek ,Black Pepper ,Garlic ,Salt ,Fennel and Poppy
Rajah Mild Madras Curry Powder

Ingredients: Coriander, Turmeric, Garlic, Bengal Gram, Chilli, Yellow Mustard,
Fenugreek, Bay Leaves, Salt, Cumin, Fennel, poppy seeds and curry leaf.
TRS Mild Madras Curry Powder

Ingredients: coriander, turmeric, chilli, mustard, cumin, pepper, fenugreek, garlic, salt and fennel
East End Mild Madras Curry Powder

Contains:
Coriander, Cumin, Turmeric, Salt, Fennel, Red Lentils, Chilli Powder, Bay Leaves, Fenugreek Powder, Cinnamon, Garlic, Cloves
Natco Medium Madras Curry Powder

Ingredients: Coriander, Turmeric, Cumin, Salt, Gram Flour, Chilli, Mustard, Fenugreek, Fennel, Garlic, Black Pepper, Star Anise.
Lalah's Madras Curry Powder

Ingredients include: coriander, turmeric, mustard, chillies, bengal gram (chana dal), cumin, fenugreek, pepper, garlic, salt, fennel, poppy seeds and curry leaves
Ship Brand Madras Curry Powder

Ingredients: Coriander Seeds, Turmeric, Chillies, Cumin Seeds, Fenugreek Seeds, Fennel Seeds, Trifala & Nagkeser (Fragrant Spices), Cloves, Cassia, Garlic, Curry Leaves and Salt.