I, however, found a few that have multiple Sun+RA and also the surface of the gummed side of one of them is very smooth - whereas the printed side is roughy and the fibres visible. This indicates a transposed watermark [filigrana traspuesta] or in other words the stamp got printed on the wire side of ther paper. Usually the felt side of the paper gets printed and that is where the watermark was applied.
The front of ther stamps:



The AЯ watermarks:



The RA watermarks:


