Stuart Armstrong
Yes, many times a woman goes by more than one name. Or parts of her full name. Her full name could be Antonia Catalina Avila Cid. But don't jump to that as the only solution. People changed or modified their names often, so that in later records you may not recognize the same person found in earlier records. I have several instances of females having as many as seven different surnames in various records, along with several variations of their given names. Whether it was that they had decided to be known by different names, or that the informants were not well informed, is hard to tell. I can certainly relate to your dilemma trying to decide if the two names belong to the same person.
Name variations seem to be more common with women than men. Perhaps it was because of the culture of the times, that the women were often not present at the christenings of their children, being "churched" or recovering from childbirth, and those present may have known her by her first name only. Remember - in many instances these were very poor people, almost slaves, and working hard to survive. And most of them were also illiterate.
Another reality which causes confusion many more times than you would expect is two siblings who have the same name. In my wife's direct ancestral line there is a Timoteo Puentes, who had a brother with exactly the same name. At first I thought he was married twice, until I noticed that the children of the two wives overlapped. One Timoteo married Severa Rodríguez and the other married Arcadia Zapata. To make matters worse, Severa had a sister named Severina, which you would expect to be a variation of the same name. And to make it even more confusing, one of the priests in the original records confused the wives of the two brothers and came up with Severa Zapata, leading one researcher to think they were the same person, and combining the names into Severa Arcadia Rodríguez Zapata. It took a lot of evidence to unravel the confusion and prove that some of the original records were wrong.
I have about six such instances of same-name siblings in my database. In one case there were THREE siblings of the same name. This scenario most commonly happens with twins, or with a child who was born on an older sibling's birthday. It does NOT usually mean that the older child had died - in most cases the siblings were contemporary and each raised their own families.
I might also point out that most of the "original" records were not really original. They were copied from other volumes or loose papers months or even years after the fact. Internal evidence reveals many typographical-style errors, parts of records ending up in other records, names and relationships missplaced, dates that don't make sense, gender errors (lots of them), etc.
My conclusion, then, is that you just have to keep on gathering evidence, until you get enough that hopefully the true picture will begin to emerge.

It's not uncommon for a person to be referred to with two different names.
i.e. Juan Antonio Carlos's parents are Jose Carlos and Maria Carrillo. He can be referred to as either Juan Carlos or Antonio Carrillo. I've seen this many times.

Jose Carlos de Leon

I believe these are two different women-- wives of the same man. I'm sure someone recording the vital information perhaps mixed up the names sometimes, but I don't think there is only one woman. What makes you think so?