Nothing fancy.
International Postal Supply Company machine cancels, both of them.
As a likely scenario, the card went through the machine with a misfeed partly overlapping another mail piece (cards are thinner than letter-mail and double-feeds are more likely), getting only the wavy line killer portion from machine 5, 6, 15 or 16.
A clerk noticed it lacked a dial impression and sent it back to the machine operators where it went through machine 10 getting the full dated impression.
Add: Here is an example with two full machine cancel impressions, but making a similar killer impression. The card was sent out as a bill, returned under-cover with payment, then re-stamped and re-mailed back as a receipt.
