A: That's possible. It's possible also that two works can strengthen each other. But it depends entirely on the details of the work. Let me give you an example. A client comes to me and wants help with a not-quite-law-abiding cousin who is making trouble for her family. The client does not choose to have a reading first and is not very verbal about how she'd like this to happen, and isn't forthcoming about previous work she's had done or is currently having done, and she has a strong Catholic background that's been in her family for generations. So I decide to do ancestor work to call in a family spirit to strengthen the blood ties in the family and heal them, so that the cousin will come to his senses and stop hurting his own kin, and I ask St Michael to stand in and protect the family from outside and inside harm and help it mend its own wounds so that these troubles will stop. The goal is healing and strengthening of the family from within, and I've called an ancestral spirit in to the job, and I've called a warrior angel in to protect the family from interference so it can have time and space to work through its issues.
Meanwhile the client goes to another worker, doesn't tell the worker that she's having other work done, and presents the same problem. Now, this worker doesn't come from a Catholic background herself, and she happens to specialize in protective and defensive magic, so she decides to do Reversing and Hot Foot work on the troublesome cousin to get him away from the heart of the family so he won't be bringing the cops around the house anymore. The client doesn't actually understand enough about hoodoo to understand that she now has hired two workers who are canceling each other's work out. The client thinks she has two good people on her side, and she is in the mindset of "more is better," but in fact she has wasted her money twice and wasted the time of both workers, because one is sending the cousin's negative stuff back on him and trying to run him off, while the other is calling on family spirits to heal the family, and on St. Michael to protect the family from evil - *including their own,* meaning St. Michael is deflecting the Hot Foot work.
Now this is a sort of extreme example, and it's true that in some cases, if you hire two workers they will end up doing the same work. But folks err in coming from the "if one is good, two are better" mentality. You have not just hired somebody to clean your house, so a second person cleaning get its cleaner quicker; what you've done is more akin to hiring two attorneys to take the same case. They are going to duplicate work unnecessarily and trip each other up, and they could in fact screw each other's work up. This is why you shouldn't ever have two people working your case at the same time unless everybody knows what is going on, what kind of work is being done, and is on the same sheet of music.
It's potentially wasteful and potentially dangerous - like getting prescriptions from two doctors and not telling them about the other prescription. Also, it's a question of professional courtesy. Your rootworker is not your paid servant, to be at your beck and call to cut your grass or wash your car; if you expect to keep a bunch of workers in a stable ready to do your whim at the drop of a hat, you have the wrong idea. If you try to treat your worker like your paid staff, your worker is likely to fire you as a client. Your rootworker is a professional with more experience and perspective than you on the dynamics of your case, who has seen the ins and outs of dozens or hundreds of cases like yours. If you want a second opinion, by all means get one. If you have an inexperienced worker, or a bad one, or even one who you just don't click with, then by all means get a second opinion. But don't hire multiple workers at the same time, to work the same case, without being honest and making sure it's ok with everybody involved.
If word gets around that you are someone who will hire multiple workers for the same case without being forthcoming about it, some workers will refuse to work with you. There are lots of reasons for this, some of it the potential work conflicts, but also it suggests that you are not giving your spellwork enough time to manifest and/or are not following directions, or else, if you have given it time and you did follow directions and the spell didn't work, then it suggests you are not communicating with your spellworker but are just hopping to a new one. (I'm not saying this is always what happens - but I am telling you what we tend to worry about when we hear about clients hiring different people to do the same work.)
So I advise folks to never, never hire two workers without being clear what has been done and is being done. Some workers will co-consult a case with another worker. Some will not and will furthermore be extremely insulted if you ask them to (not necessarily because they take it as a lack of faith on your part, but because co-consulting is usually quite time consuming, and you are asking a rootworker to possibly double the amount of time they put into your case with no corresponding increase in the fee they are receiving for their time. And you are also assuming that they get along with the other worker and have a compatible approach and communication style. It's not safe to assume any of this).
Bottom line: if you are going to hire a professional, don't backseat drive. Do your research, consult with them thoroughly, get your questions answered ahead of time, sure. But once you hire them, get out of the way and let them do their job. If you don't trust them, and/or if you want a second opinion, and/or you want a different approach from a different worker, then tell them this. Let them know, clearly, that your work together is done, or even that you are seeking a second opinion. Don't keep the people working your case in the dark. It's not good for your reputation as a client (and trust me, clients get reputations just like workers do!), it's not good for your relationships with your workers, and it's not good for your case.