It is not unusual to see two ...

It is not unusual to see two identical wells perform differently on the same site. It sounds to me as though groundwater is being accessed via fissures and fractures within the wells and it may simply be that the more productive well penetrated more fractured ground, gaining greater flows, whilst the second well did not intercept as many productive fractures.

In answer to your question regarding sustainability, this is answered by slowing the pump speed / controlling flow until the pumping water level  stays above the pump unit by perhaps 5m. A drawdown from 57m to 176m demonstrates that the second well is simply a poor producer. If you want to try and improve things, you could try and develop it - possibly with acid if its drilled through limestone. This can help enormously...Good luck