Two Diaphragm pumps in parallel

I am working on a water system that will be pulling from a spring at ground level and will be serving about 9 fixtures, which equates to about 9 gpm (using the rule of thumb of 1gpm per fixture).  The distance from the the spring to the fixtures is about 250 feet horizontal, with an elevation gain of about 15 feet vertical.  We are looking to obtain household water pressures of about 40-60 psi and flow rates of at least 8-9gpm. 

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Is it ok to use two diaphragm pumps in parallel, to achieve the necessary household water pressures along with sufficient flow rates mentioned above?  It seems that two diaphragm pumps in parallel would be much cheaper and smaller to install than a larger, single pump capable of these pressures and flow rates.  I found the Grundfos SCALA2 pump, but at $650+, it seems somewhat expensive and it seems to have some quality control issues.  We will be grid-tied, but still value efficient pumps.

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Thoughts?

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