Thanks Deke.
The guy I have communicated with, has been compiling and gathering artists, trying to identify unknown pieces/artists and also mentioned how a number of unknowns "mimicked" / copied and in some cases trained under the well known poster artists and developed a similar style. He also said that Renau did not sign all of his poster works.
Like anything, its all part of what makes the hobby so fun, dont you think? Doing the digging and research, finding out new info and that kind of thing.
There was one signature that this gentleman wasnt familiar with (it was a couple stylized, abbreviated letters). In looking thru the EMP database, I found one Mexican poster where the capital initials of the artist's first and last name were written with the same 'flourish' but it was the whole name. I sent the pics and name down to this guy, and sure enough, he agreed that it was the same artist (it wasnt Renau). So he was able to check that "unknown" off of his list.