You have helped me. I never gave it a thought that there was a distinction. I learned something new today. I don’t know, seems like that system would lead to redundancy of expenditures.
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There are two different functions, two different government levels.
One for the US with the senators originally supposed to represent their STATE’S interests and be appointed by the state legislators and governors to the US NATIONAL government; and the second the STATE government. Normally the state governments also have two bodies as well.
Nothing duplicate about it all.