“That would be one for the books - lose re-election to one senate seat and then win election to the other senate seat two years later.”
It’s happened before. Democratic Senator Joseph O’Mahoney was narrowly defeated for reelection in 1952, than won a vacant seat in 1954.
Also Chapman Revercomb in west Virginia lost reelection after one term in 1948. he then won again in 1956 but was bumped by Bob Byrd in 1958. Also John Sherman Cooper in Kentucky was elected three times to the Senate and lost his bid for relection after each of the first two elections. But it is very rare to see a senator come back from political death.