Ah, never mind. NIP-59 mentions what you just said about sending yourself a copy.

"If a `rumor` is intended for more than one party, or if the author wants to retain an encrypted copy, a single `rumor` may be wrapped and addressed for each recipient individually.”

https://github.com/nostr-protocol/nips/blob/734f379a2a2f225f76f87cdcf074c997a0d40d35/59.md?plain=1#L82-L83