That’s one reason.Isn't that because they realize that the way they ask questions about your opinions and thoughts and feelings often change regarding how they word the question? I've typically seen that done and then the score for that parameter was a combined function of all the similar questions.
Other reasons include testing the respondents’ actual understanding of the question asked. Sometimes, people will answer a question even if they don’t actually understand it. Sometimes people are unfamiliar with the particular terminology used, but again, would still answer.
To use a nonpolitical example, a pollster might ask:
”How many people has SARS-CoV-2 killed?”
then
”How many people have died from Covid-19?”
then
”How many fatalities have been caused by the novel coronavirus?”
Getting radically different answers to those three question could indicate the efficacy of government healthcare briefings. It could also be an indicator of what kind of news sources the respondents favor.