The first strike, which took place on Tuesday, led to widespread delays and disruption to Tube services across the capital.
Some lines were wholly or partly suspended while others had fewer services than normal.
Transport for London (TfL) continues to advise people to check before they travel for the rest of the week.
More disruption is set to hit the city this summer, with further 24-hour strikes planned in May and June unless the row is resolved.
Pubs and restaurants across the capital have said they fear losing trade this week because of the industrial action as fewer workers than normal have travelled to offices.