  We report on photometric observations of WZ Sge-type dwarf novae, MASTER OT
J211258.65+242145.4 and MASTER OT J203749.39+552210.3 which underwent outbursts
in 2012. Early superhumps were recorded in both systems. During superoutburst
plateau, ordinary superhumps with a period of 0.060291(4) d (MASTER J211258)
and of 0.061307(9) d (MASTER J203749) in average were observed. MASTER J211258
and MASTER J203749 exhibited eight and more than four post-superoutburst
rebrightenings, respectively. In the final part of the superoutburst, an
increase in the superhump periods was seen in both systems. We have made a
survey of WZ Sge-type dwarf novae with multiple rebrightenings, and confirmed
that the superhump periods of WZ Sge-type dwarf novae with multiple
rebrightenings were longer than those of WZ Sge-type dwarf novae without a
rebrightening. Although WZ Sge-type dwarf novae with multiple rebrightenings
have been thought to be the good candidates for period bouncers based on their
low mass ratio (q) from inferred from the period of fully grown (stage B)
superhumps, our new method using the period of growing superhumps (stage A
superhumps), however, implies higher q than those expected from stage B
superhumps. These q values appear to be consistent with the duration of the
stage A superoutbursts, which likely reflects the growth time of the 3:1
resonance. We present a working hypothesis that the small fractional superhump
excesses for stage B superhumps in these systems may be explained as a result
that a higher gas pressure effect works in these systems than in ordinary SU
UMa-type dwarf novae. This result leads to a new picture that WZ Sge-type dwarf
novae with multiple rebrightenings and SU UMa-type dwarf novae without a
rebrightening (they are not period bouncers) are located in the same place on
the evolutionary track.
