That's not how masks work. The masks rating is mostly a function of leakage not filter material for the particles of concern (biological aerosols) and using mul

That's not how masks work. The masks rating is mostly a function of leakage not filter material for the particles of concern (biological aerosols) and using multiple harder respirators can compromise fit or provide no benefit. The rating percentage is for specific test setup. For biological aerosols, the result is quite different in that small particles are stopped by diffusion, and the filter rates tend to be better than rated for masks, as long as leakage is low. Now, the situation is different with weak filtering materials such as used in surgical or cloth masks, but the result is not additive either. Have you actually tested that the specific double N95 configuration even provides single N95 protection? (Esp. leakage) No? Then better not mess with the design.