It really depends on how obvious it is, like someone using your gig images too and how many people are using the exact same description. If you can send some proof to CS regarding when you created and added your described and/or CS is able to see that yours was first, they will usually make the other sellers change theirs. If its hard to prove or lots of people are using the same one it might be a bit tougher.
In the long run you can still try CS and if they don’t make the other people change, just make yours even better and save proof of the date and time. Use it to your advantage. I don’t know what your services are, but if you aren’t a strong marketing writer you could even hire a copywriter to make your gig description really awesome and then you’d have extra proof that you own the description. Regardless, the first step is just to contact CS and complain about the copycats.