Workers at Benefits Agency offices and Jobcentres in Brighton and Hove are expected to join a 48-hour strike next week.
The Public and Commercial Services Union (PCS) has called the stoppage, scheduled for Monday and Tuesday, in a dispute over safety.
Workers in England, Scotland and Wales walked out for two days in December, claiming managers had not addressed safety fears about the new combined Jobcentre Plus offices.
PCS organiser in Brighton Martin Smith said his members risked being attacked in the new open plan offices, which will not have screens between staff and clients.
He said: "PCS members regret having to take this action but while management have stalled negotiations the attacks on staff in Jobcentres and benefits offices continue week on week."
The Department of Work and Pensioners said it was a futile dispute and the new-look offices were the way forward.
A spokesman said people who used the service were unlikely to be affected by the strike.
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