Hi Rhonda,
I know exactly how you feel about being confused when trying to put together a very difficult puzzle of our ancestors and how the norm was for them way back then. I hope what I tell you can help you, at least help you understand their names a bit. There may be another person who will reply to your message who may be able to clarify it better than me, but at least you'll have a tad bit of understanding if that happens :)
What I have learned through the many, many hours of research, reading, and talking to family members is the custom way of their names. When a child is born, the parents will name that child at the time of birth (I'll use me and my family as examples). So my parents names are Robert Guzman and Diane Beitler (maiden name always used when a child is born). My name would therefore be...Crystal Beitler Guzman. I would keep that name until my baptism day, which could be the same day at only 2 hours old or it could be 2 days later, but I would hold that name until my baptism date. When I get baptized (for some reason) my parents would then change my name, under the eyes of God, to Crystal Marie Guzman. Marie being my "baptized name". I hope I haven't lost ya yet! Here's another quick, but different, example, my great grandmother was the daughter of Ignacio Verduzco and Maria Soto, her name was Maria Luisa Verduzco. When she was baptized 2 days after birth her name then became Maria Luisa Josefa Verduzco. Not too sure why she kept Verduzco considering her mothers maiden name was Soto...just another mystery here in our search for our ancestors I suppose. When my great grandmother came to America from Mexico she travelled under her married name; Josefa Cortez. She travelled with her two children and husband; Marciano Cortez . She never used Maria Luisa ever again on any proper document for the rest of her life...and she lived to be 105 years old!! WOW!
The names I have used for examples are all true. I had searched and search, high and low, for Josefa Cortez and Josefa Verduzco until I finally broke down and decided to pay for my membership on this site again. Back in 2000 there weren't as many documents from Mexico or very much information to any names that were provided. My 2nd cousin, great grandma's grand daughter, was raised by Josefa and she was able to give me my great grandma's name, thank gawsh for that or I'd still be going crazy from searching for any type of birth using only "Josefa Verduzco"! Like you, I have found documents spelling her maiden name as Berduzco or Berdusco but I know for a fact it was Verduzco at the time of her birth. There's always typos that happen during transcribing old documents that were had written so the possibilities of your mis-spelled names is very common. We also have to take into consideration that back in those days many people couldn't read/write or both, like you said, so they would tell the official person writing the paper what their names were. The proper person would write it down as they hear it. So Verduzco is said in a different way when using the native tongue of Mexico sounding like Berdusco. The V is pronounced as a B and the Z is pronounced as an S in the spanish language. Knowing this makes the typo a little more logical.
It's all quite confusing but I really hope I helped a little bit. If you have any questions, please feel free to ask away! I'm not a pro at this but this is just some of the things that I have learned through all of my hours of reading and searching.
Have a great day!
Crystal Guzman :)