  Polarimetric studies of pulsars at low radio frequencies provide important
observational insights into the pulsar emission mechanism and beam models, and
probe the properties of the magneto-ionic interstellar medium (ISM). Aperture
arrays are the main form of next-generation low-frequency telescopes, including
the Murchison Widefield Array (MWA). These require a distinctly different
approach to data processing (e.g. calibration and beamforming) compared to
traditional dish antennas. As the second paper of this series, we present a
verification of the MWA's pulsar polarimetry capability, using two bright
southern pulsars, PSRs J0742-2822 and J1752-2806. Our observations
simultaneously cover multiple frequencies (76-313 MHz) and were taken at
multiple zenith angles during a single night for each pulsar. We show that the
MWA can be reliably calibrated for zenith angles < 45 degree and frequencies <
270 MHz. We present the polarimetric profiles for PSRs J0742-2822 and
J1752-2806 at frequencies lower than 300 MHz for the first time, along with an
analysis of the linear polarisation degree and pulse profile evolution with
frequency. For PSR J0742-2822, the measured degree of linear polarisation shows
a rapid decrease at low frequencies, in contrast with the generally expected
trend, which can be attributed to depolarisation effects from small-scale,
turbulent, magneto-ionic ISM components. This effect has not been widely
explored for pulsars in general, and will be further investigated in future
work.
