  The Raman 2D line of graphene is widely used for device characterization and
during device fabrication as it contains valuable information on e.g. the
direction and magnitude of mechanical strain and doping. Here we present
systematic asymmetries in the 2D line shape of exfoliated graphene and graphene
grown by chemical vapor deposition. Both graphene crystals are fully
encapsulated in van der Waals heterostructures, where hexagonal boron nitride
and tungsten diselenide are used as substrate materials. In both material
stacks, we find very low doping values and extremely homogeneous strain
distributions in the graphene crystal, which is a hall mark of the outstanding
electronic quality of these samples. By fitting double Lorentzian functions to
the spectra to account for the contributions of inner and outer processes to
the 2D peak, we find that the splitting of the sub-peaks, $6.6 \pm 0.5$
cm$^{-1}$(hBN-Gr-WSe2) and $8.9 \pm 1.0$ cm$^{-1}$ (hBN-Gr-hBN), is
significantly lower than the values reported in previous studies on suspended
graphene.
