Pingdom speed test downloads both woff2 and woff of the same font

Question

I noticed when running Pingdom speed test and viewing the file requests section, the test server downloads both .woff2 and .woff versions of each font from my site, declared using the standard @font-face css like below:

@font-face
 {
  font-family:'Roboto Condensed';
  src:url('../fonts/roboto-condensed-v16-latin-regular.woff2') 
  format('woff2'),url('../fonts/roboto-condensed-v16-latin-regular.woff') 
  format('woff');
  font-weight:400;
  font-style:normal;
 }

(I self host the Google fonts.)

So basically with 8 fonts used the test server requests 8 extra .woff files it doesn't really need.

Why is this happening? I tested the site using Chrome/Firefox developer tools and only .woff2 is retrieved as expected. Is this a bug with Pingdom?

Interestingly, I noticed that the test server only requested the .woff2 version of FontAwesome, even though the fontawesome css also referenced both .woff2 and .woff versions.