Your phrasing makes that a trick question.
The hifi feature in VCRs that have it has always been stereo, so the answer to the question (as you phrased it) is yes on both counts: the 620 has hifi audio and it is stereo capable (plays/records in hifi stereo).
But I'm guessing your question is really about the backup, standard linear audio system: you want to know if the 620 can play the handful of ancient non-hifi linear-stereo tapes in stereo. That answer is no. The non-hifi, linear stereo feature died out the moment the first hifi VCRs hit the streets back in 1985. Since then, virtually no commonly-available consumer VCRs have been able to play or record in linear stereo: only linear mono and hifi stereo/mono. (There may have been one or two odd ducks from Aiwa, etc, and some pro-level decks from JVC, Panasonic, and Sony, but nothing you can pick up now at reasonable cost in good working condition.)
If your question is whether the 620 includes a stereo tuner, the answer is again no: it has no TV tuner at all. It records only via line input from external tuners, cable or satellite boxes, or an external VCR. If those sources are sending the 620 a stereo audio signal, the 620 will record it in hifi stereo with the backup linear track being a mono mixdown.
FWIW, the recent reviews
of this model on Toshiba's own website are pretty dismal regarding the VCR. I'd be leery of loading any irreplaceable tapes until you're sure its working reliably.