  Although most gravitational wave events are claimed to be mergers of
unusually massive, $25-65M_\odot$, black holes, it is now clear that 20\% of
all reported events comprise modest mass black holes, $5-15M_\odot$, like the
stellar black holes in the Milky Way. We show that such stellar mass black hole
binaries (BBH) if magnified by lensing galaxies can be detected at high
redshift, 1$< $z$ <$5, with chirp masses increased by $1+z$, accounting for the
majority of apparently high mass BBH events. This simple lensing explanation is
manifested by the evident bimodality of BBH chirp masses now visible, with 80\%
of BBH events in a broad peak centered on $m_{chirp} \simeq 35M_\odot$, and
20\% of BBH events in a narrow, low mass peak at $m_{chirp} \simeq 8.5M_\odot$,
matching well our prediction for lensed and unlensed events respectively. This
lensing interpretation is reinforced by the "graveyard plot" when ranked by
chirp mass, revealing a jump in chirp mass at $m_{chirp} \simeq 10M_\odot$ that
we show is caused by the large redshift difference between unlensed events with
$z<0.3$ and lensed events above $z>1$. Furthermore, nearly all BBH events are
seen to share a component mass ratio of $m_1/m_2=1.45\pm0.03$, indicating a
common stellar origin for BBH events across all chirp masses. This observed
component mass uniformity implies most binary black holes seldom pair up by
random capture, instead we may conclude that massive progenitor stars of BBH
black holes typically formed in-situ, in a well defined way over the full span
of cosmic time accessed through gravitational lensing.
