Check out the docstring of variable `org-capture-templates`.
There is a doc like this:
```
%\1 ... %\N Insert the text entered at the nth %^{prompt}, where N
              is a number, starting from 1.
```
Maybe this is what you want?

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On Fri, Jun 30, 2017 at 5:14 PM, Jean-Christophe Helary <jean.christophe.helary@gmail.com> wrote:
I'm looking for a way to use the string acquired by prompt in a second location in the template, like:

* TODO %^{prompt} [/] :sometag:\n** TODO (value of ^{prompt} comes here) :someothertag:\n

What's the best way to get that "value of ^{prompt}" ?

Jean-Christophe