No, Cheratussin AC should not be taken along with benzonatate. Cheratussin contains codeine, and taking it with benzonatate may result in additive effects, putting you at risk for adverse reactions.
The main concern regarding the use of benzonatate with Cheratussin is the additive sedation that could occur, along with the increased risk of major side effects such as respiratory depression. Although this isn't common, it is important to be aware of, especially if there are any underlying conditions. In addition, both drugs are used for the same indication, to help reduce the symptoms of cough. There is no evidence that taking both together would result in a greater effect than taking one alone.