IMHO, that WaA stamp is spurious.
Are you saying that because you think it to be too sloppy? It does appear to be double stamped, or "bounced" if you will. However, given the SN of the gun being 253520, its not really possible to be spurious. I never heard of any bad ones being in the correct SN ranges for these. The bad ones are mostly Bulgarian contract guns from what I gather.
Per Still in Axis Pistols Vol II 2nd ed, the lot 19 delivery was SNs from 248001 to 254300 and then from 254551 to 256250. Also, the same SN range is given in Gangarosa's book, Spanish Handguns.
Thanks to your question, I found out that my pistol is in fact a 4th variation, not a 3rd variation as I originally stated.
Here is a photo of a 253XXX range gun. The mark is a little neater, but the SN is firmly in the right range for the contract, which eliminates other possibilities. This one was also made after mine if you compare SNs.