Dúvida means doubt only sometimes.
We say, “without a doubt” for “sem dúvida.”
But we do not say “I have a doubt”, when we want to ask for information.
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We say, “I have a question,” for “Tenho uma dúvida”.
People who are studying English like to say, “I have a doubt.” That is one of the most common mistakes that even advanced learners make.