The first 5c Moreno with 'Servicio Oficial' overprint dates from 1938 and is found on the 1E1 typographed stamp, somewhat common as a regular stamp yet surprisingly uncommon as an used official stamp.
Here is statement dated in 1938.
This printing is from a very dirty plate.
The second 'Servicio Oficial' issue is in offset on the 1E3 paper.
This specific stamp has a small break in one of the lines in the background of the bust, and a scratch to the plate outside of the stamp design.