SREQ and DOG set in RESETREASON register

We have fairly regularly observed that the reset reason register gives two reasons for reset: software request and watchdog.

Is it plausible that these bits are genuinely set at the same time? If so, under which conditions?

Alternatively, is it possible that this register accumulates reasons and we are supposed to clear them?

Our software consists of a bootloader (the one shipped with the thread support SDK) and an application image.

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