Most fiats after 2001 do not require a red key. Instead it was two blue keys. These two blue keys carry all the immobiliser and information the red key used to do.
The only exception to this was the bravo/a which had a red key from the beginning to end of life.
I am unaware of what the doblo is, i would expect it to be 2 blue keys, however maybe posting in the doblo section will get you a dfinitive answer
I would question why there is only one blue key though, if it turns out to use 2 blue keys.