I think these situations are more common than one thinks.
It all depends on the terms of the various pension plans regarding retirement.
Say a policeman can retire after 30 years of service. He or she does so and retires at say age 55. There is probably nothing in the plan that prohibits that person from taking another job in the city and working until age 65 or so and then collecting another pension.
Happens all the time in and around Our Nation’s Capital
This is routine among LEO and FDs here in Cali. It’s also legal to do and shpuld be illegal imho.