Is this a follow on from your earlier post? -
If I understand you correctly you're asking do we need to have 2 x 100%?
There is no absolute in this - it depends on what your operational issues are and the consequences of one unit not working. Only you and the client know that.
The factors would include cost, space, control equipment to turn one off / auto switchover from duty to standby, actual capacity of a single pump, consequence of failure, time to repair / replace, how often they are needed, run time per year, probability of failure / reliability, maintenance undertaken, testing of operation, confidence about the maximum inlet flow etc.
I have seen a few systems where influx of water is such that to cope with the rare peak demand, you have 2 x 100%, but if one is overwhelmed then you have 2 x 100%, but haven't oversized the pumps and power supply.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.