Inbound messages to a single workmail mailbox being duplicated

Heya folks,

We use Workmail, probably about 50 mailboxes in use currently. In the last couple of weeks we have started seeing sporadic inbound emails being duplicated in the inbox if just one account. Super weird, it's a shared mailbox, nothing has changed that I am aware of / can tell. If it was a system issues (SES Inbound rules, etc.) then I would obviously expect it to impact all mailboxes, but the fact that it's just this one has me at a loss.

It appears to be primarily / mostly external emails being received, though I have anecdotal evidence of at least one internally generated email (an email systemically generated and sent through SES) that received in a duplicated fashion as well.

Anyone seen anything similar?

Thanks!