I've been collecting Spain for a number of years and was always under the assumption that Spain did not have any precancels, until I read this in Theo Van Dam's book "A Postal History of Spain":
"7. PRECANCELS (Franqueo Concertado)
In 1879 a system for pre-cancels was used for a short time, known as "Franqueo Concertado" (lit. "franking by agreement") with the 1878 and 1879 Alphonso XII (Scott Types A31-33) issues, and very rarely on the 1889 Alphonso XIII "Pelon" or "Babyhead" stamps (Scott Type A34).
The system consisted of monthly payments on account for the postage due. This amount was paid in sheets or large blocks of adhesives, which were cancelled at the Correo Central (Main Post Office) in Madrid with an hexagonal marking. This accounts for the large multiples of the 1879 and 1882 issues often with original gum."
Then I found this entry in the book "Billig's Handbook on Postmarks, volume 13, The Postal Markings of Spain", also by Van Dam, that pertains to the same thing including a sample of the marking.
Then I did some searching in my stash of duplicates and found a few of what I believe to be these "precancels".
The 4 Una Peseta stamps on the left appear to be a block of 4 that have been broken apart, but on closer examination of the cancels they are actually 4 different sections of the same type of cancel. They also have full gum. The one on the right has no gum.
I'm not sure if these are considered "pre-cancels" like what are normally seen elsewhere, but Theo Van Dam seemed to think they were.
So I guess Spain did issue at least a type of pre-cancel.