Question about renting(important)

My tenancy ended and I forgot to return my keys to my landlord so I’ll have to pay fees for new ones and that’s fine it’s their right.
Now my question is once I return to the country
They want me to return the old keys , do I have to return them for free ?
Like I don’t feel it’s right for me to return the old keys for free.

So if I had lost my keys, it would only be to pay fees for new ones

But since I have them I’m just not not in the country at the moment
They want me to pay the same exact fees plus return them the old ones

Which doesn’t make sense.
I deserve to pay less fees at least since I’m returning the old ones
In fact I am not obliged to return anything since I’ll already pay for brand new keys .

What do you think?