In some special cases, Romans held lower offices than some they had already held, for example Quaestor while having been a consul before.
I understand that senators, expelled by the censors for various reasons, had to gain entry to the senate once more and tried to restore their former rank by starting the cursus honorum anew.
There is also the case of Agrippa, being Aedilis while consular for the purpose of urban works.
Other than that, I can't find examples of Romans willingly going down the cursus honorum ladder. That is puzzling to me, as huge advantages were to be gained (i.e. the opportunity of staging the Roman games, provincial commands after the Praetorship, etc.). Beside that, a consular holding a second Quaestorship, for example, remained consular, so there was no rank loss.
The same is true for the tribunes of the plebs. Obviously, their vetoing power (and more) should have been tempting for consular plebeians.
Are there examples of senior politicians having tried to hold junior offices and/or tribunate of the plebs?
I'm also interested in examples of Romans holding several times the same office before going up (e.g. Quaestor-Aedilis-Praetor-Praetor-Consul).