Odd space in output

[Morten Bo Johansen]

Sorry for the only partially descriptive subject ...but if I do

   parallel echo ::: {a..b} ::: {a..b}
   
to get some permutations of the letters a-b, then the output
reads

  a a
  a b
  b a
  b b

I know tr -d ' ' but why the space between the letters?
  
  Morten

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