Is “Was Liu Dai, sent by Cao Cao to attack Liu Bei, the same person as the former Inspector of Yanzhou?” true?

They are not the same person. The official history 'Records of the Three Kingdoms, Annals of Emperor Wu' records that Liu Dai, the Inspector of Yanzhou, was 'indeed killed' when he met the Yellow Turbans, while Cao Cao 'sent Liu Dai and Wang Zhong to attack' Liu Bei. These are two generals with the same name. In Chapter 22 of 'Romance of the Three Kingdoms', the two are conflated, saying: 'It turned out that Liu Dai was formerly the Inspector of Yanzhou, and when Cao Cao took Yanzhou, Dai surrendered to Cao Cao, who employed him as a partial general, so now he was sent with Wang Zhong to lead troops.'