Everybody agrees that the Spanish digraphs "ch" and "ll" used to be officially separate "letters" up to the time the RAE changed the rules of Spanish alphabetization in 1994.
But when it comes to the digraph "rr" it seems there is a lot of confusion and conflicting information on whether it was also formerly an official separate letter.
I remember learning that "rr" unlike "ch" and "ll" was not considered a separate letter despite also representing a single sound. I always remembered it because it seemed so oddly inconsistent.
But now that I do some searching on the Internet I do find lots of people asserting that "rr" was a separate letter. I do also find the opposite and I find some debates and arguments. But most of this is in English where I would expect a greater degree of wrong information. I don't think my Spanish is good enough to do Internet searches on this topic.
So I'm not asking for opinions and I'm not asking about pronunciation or spelling. Since Spanish has an official language academy I'm only asking specifically, "Was "rr" ever considered officially a letter of the Spanish alphabet?"
rrdoes not represent a different sound than non-intervocalic
r; which makes it more of graphism of the same letter in an specific setting (the same way than "ga, gue, gui, go, gu"). But nice question.