sys.path includes python3's dist-packages

I have installed pypy3 and python3 the standard way with aptitude on Debian. My pypy3 sys.path contains '/usr/lib/python3/dist-packages' Supposedly this is because pypy3 works with any pure python3 package. But for compiled packages this may fail, and the visibility of such packages from python3 prevents pypy3 -mpip install to succeed, since the package is already there. Is there a standard workaround, or have I misunderstood something with respect to installing and configuring?

Example: With python3-numpy installed, try to use it in pypy3 and then try to install it with pip.