How to re-use plural translation rule anywhere using angular-localize

Question

I have a working plural translation

<strong i18n="@@filesCount"> {(filesLength | async), plural,
  one {{{filesLength | async}} file}
  few {{{filesLength | async}} files}
  many {{{filesLength | async}} files}
  other {{{filesLength | async}} files}}
</strong>.

This generates two records in .xlf file

    <unit id="filesCount">
      <segment>
        <source> <ph id="0" equiv="ICU" disp="{(filesLength | async), plural,
      one {{{filesLength | async}} file}
      few {{{filesLength | async}} files}
      many {{{filesLength | async}} files}
      other {{{filesLength | async}} files}}"/> </source>
      </segment>
    </unit>
    <unit id="5092638633340153588">
      <segment>
        <source>{VAR_PLURAL, plural, one {<ph id="0" equiv="INTERPOLATION"/> file} few {<ph id="1" equiv="INTERPOLATION"/> files} many {<ph id="2" equiv="INTERPOLATION"/> files} other {<ph id="3" equiv="INTERPOLATION"/> files}}</source>
      </segment>
    </unit>

My question is - how do I use this exact translation rule again without having to write it again?

Also, why does it generate two records and what am I supposed to do with the first one?