Steinberger GM-3TA doubleneck red (1991)
Pictures
A gallery of Steinberger guitars, owned by European guitar and bass players.
This is probably the only GM doubleneck which came with a lined fretless neck ex works. So far I haven't found ANY hint or evidence for another LF neck on a GM at all.
This guitar is in a beautiful and mint condition, hardly played at all. Came with two HazLabs boards and two TransTrems. However, I'm still not sure what the point of a TT on a fretless guitar is, other than using it for fixed transposing settings ;-)