Apenas mais uma opção com tee
:
cat original.txt | tee blah.*
E aqui está um caso de teste que você pode experimentar em casa, sob a supervisão de um adulto responsável:
$ echo "rawr" | tee blah.{1..99}.txt
rawr
$ ls
blah.10.txt blah.26.txt blah.41.txt blah.57.txt blah.72.txt blah.88.txt
blah.11.txt blah.27.txt blah.42.txt blah.58.txt blah.73.txt blah.89.txt
blah.12.txt blah.28.txt blah.43.txt blah.59.txt blah.74.txt blah.8.txt
blah.13.txt blah.29.txt blah.44.txt blah.5.txt blah.75.txt blah.90.txt
blah.14.txt blah.2.txt blah.45.txt blah.60.txt blah.76.txt blah.91.txt
blah.15.txt blah.30.txt blah.46.txt blah.61.txt blah.77.txt blah.92.txt
blah.16.txt blah.31.txt blah.47.txt blah.62.txt blah.78.txt blah.93.txt
blah.17.txt blah.32.txt blah.48.txt blah.63.txt blah.79.txt blah.94.txt
blah.18.txt blah.33.txt blah.49.txt blah.64.txt blah.7.txt blah.95.txt
blah.19.txt blah.34.txt blah.4.txt blah.65.txt blah.80.txt blah.96.txt
blah.1.txt blah.35.txt blah.50.txt blah.66.txt blah.81.txt blah.97.txt
blah.20.txt blah.36.txt blah.51.txt blah.67.txt blah.82.txt blah.98.txt
blah.21.txt blah.37.txt blah.52.txt blah.68.txt blah.83.txt blah.99.txt
blah.22.txt blah.38.txt blah.53.txt blah.69.txt blah.84.txt blah.9.txt
blah.23.txt blah.39.txt blah.54.txt blah.6.txt blah.85.txt
blah.24.txt blah.3.txt blah.55.txt blah.70.txt blah.86.txt
blah.25.txt blah.40.txt blah.56.txt blah.71.txt blah.87.txt
$ cat blah.67.txt
rawr
$ echo "hooray" > original.txt
$ cat original.txt | tee blah.*.txt
hooray
$ cat blah.67.txt
hooray