Oh sorry, I thought you were conflating the two because the talent you described was for mirror writing.

I'm also left-handed and learned belatedly that I can do mirror-writing with my non-dominant right hand. I'm not that coordinated with that hand, so the writing is a bit messy, but it doesn't seem to require noticeable extra cognitive effort to do the mirroring.

I could also pretty easily read upside down or backwards from around the time I learned to read.

However, I've never found it easy to make ambigrams!