I don't think that one person should be able to run for two political offices...but it is up to the people of each state to put a end to it.
I don't believe the states can put term-limits or any other types of limits on federal office. It would require a constitutional change.
Nevertheless, I agree with you. You should only be allowed run for one federal office at a time, especially since you are not allowed to hold but one office at a time.