First time I've seen anything like this (in multiple ways.)
Here is what I do know: It is clearly of the 1894-1895 Rocafuerte style (obvious.) The regular issues of that set are Orange though.
The 1894-1895 Officials are all black, as this one is, but all have the "Franqueo Official" in red across the top.
The cancel is a bit harder to understand; it looks like a pen cancel, but it is pretty darn straight.
The stamp does have original gum, but is hinged; leading me to think it was not postally used and then soaked off a cover.
Anyone have a guess?