I found this while researching this same question.
“It takes us six weeks to make Seedlip,” says Branson. “We effectively use the same equipment and ingredients as our alcoholic counterpart but we use them in different ways and for different reasons.” Seedlip starts out as neutral grain spirit (NGS); each botanical is macerated in a specific style of NGS, with abv strengths and base grains differing from one ingredient to another. After maceration, each botanical is distilled twice: once to remove the alcohol through evaporation, and a second time to “bring everything else over and capture and concentrate the fantastic flavour of the plant”. That equates to 36 distillations before the distillates are blended, filtered and bottled.
https://www.thespiritsbusiness.com/2018/11/is-greater-transparency-needed-in-non-alcoholic-spirits/
