one to one double

[Gość: lelum]

seems to be an idiom, "she was one to one double"

[Gość: Steve]

The phrase is used in technical documents meaning two series of eg complex
chemical compounds having a direct relationship between the component parts of
the series. They are one-to-one: each single part in one series has a matching
part in the other series.

'One to one double ended' is advertised on sex telephone chat lines, which
presumably means that there is a conversation just between you and the paid sex
object at the other end as opposed to listening to a recording or having a large
number of people talking together.