  Double Deeply Virtual Compton Scattering (DDVCS) is the only experimental
channel for the determination of the dependence of the Generalized Parton
Distributions (GPDs) on both the average and the transferred momentum
independently. The physics observables of the electron induced di-muon
production reaction $\vv{e}^{\pm}p \to e^{\pm}p\mu^+\mu^-$ off unpolarized
hydrogen are discussed. Their measurement with the high luminosity and large
acceptance SoLID spectrometer at the Thomas Jefferson National Accelerator
Facility, using polarized and unpolarized positron and electron beams at 11 GeV
is investigated. This experimental configuration is shown to provide
unprecedented access to the GPDs with the determination of the real and
imaginary parts of the Compton Form Factor ${\mathcal H}$ in an unexplored
phase space, and to enable an exploratory investigation of higher twist
effects.
