Dated Stamp On Back Of Honduras Airmail

I know this was recently discussed somewhere, and I think it might have been discussed here, but no amount of searching has led me to the original discussion, so apologies in advance for revisiting this...at the time I read the discussion, I didn't realize I had at least one example.

This is Honduras C43, with a dated "cancel" on the back. The stamp is unused, with gum. I presume this is some sort of control mark? Yes? No? I've included the 10c value from the set for reference to the particular issue.

Thoughts? Or at least a pointer to the original discussion, if you recall it.

Thanks.

Collin